May 5 2025 Demo Ryian mohamed 0 Welcome to Optics Demo 😉 Name Email 1. Visual Function Which of the following is true about LogMar? The number of letters increases as you move down the chart A LogMAR of +1 is equal to Snellen score of 6/6 The letter spacing is equal to one letter width A logMAR of 0 is equal to a Snellen score of 6/60 None 2. Aberrations Which optical aberration is most affected when a lens is tilted? Pincushion distortion Coma Chromatic aberration Spherical aberration None 3. Prisms A prism deviates light by 5 cm at a distance of 1 meter. What is its prismatic power? 0.5 prism diopters 10 prism diopters 5 prism diopters 50 prism diopters None 4. Calculations Transpose the -4.00 DS/ -3.00 DC X 45 into positive cylinder notation? −7.00 DS/ +3.00 DCx135 −5.50 DS/ +3.00 DCx135 −7.00 DS/ +3.00 DCx45 −5.50 DS/ +3.00 DCx45 None 1 2 3 4 Time's up April 15 2025 Histopathology Ryian mohamed 0 1. Cornea Which layer of the cornea contains keratocytes? Epithelium Bowman's layer Stroma Descemet’s membrane Endothelium None 2. Retina The internal limiting membrane of the retina is formed by: Müller cell footplates Astrocytes Photoreceptor nuclei Retinal pigment epithelium Ganglion cells None 3. Retina Drusen are histopathological features seen in: Diabetic retinopathy Retinitis pigmentosa Age-related macular degeneration Uveitis Retinoblastoma None 4. Cornea The primary site of lesion in keratoconus is: Epithelium Bowman's layer Stroma Descemet's membrane Endothelium None 5. Pathology Rosette formations on histopathology are characteristic of: Retinoblastoma Conjunctival lymphoma Orbital cellulitis Choroidal nevus None 6. Cornea Which structure is acellular and acts as the basement membrane for the corneal endothelium? Stroma Bowman's layer Descemet's membrane Bruch’s membrane Internal limiting membrane None 7. Pathology Fuchs endothelial dystrophy primarily affects which corneal layer? Epithelium Stroma Endothelium Bowman's layer Limbus None 8. Pathology Psammoma bodies may be seen in histology of which orbital tumor? Cavernous hemangioma Optic nerve glioma Schwannoma Meningioma Rhabdomyosarcoma None 9. Eyelids Which type of gland is the Meibomian gland classified as? Apocrine Sebaceous Eccrine Endocrine Mucous None 10. Retina Which retinal layer contains the nuclei of photoreceptor cells? Inner nuclear layer Outer nuclear layer Ganglion cell layer Outer plexiform layer Retinal pigment epithelium None Time's up March 18 2025 Optics Ryian mohamed 0 Welcome to Optics 😉 Name Email 1. Please select your category: Please select your answer Lasers Retinal Surgery Jokes Astigmatism Instruments Low Vision Aids Clinical Visual Function Aberrations Prescriptions Prisms Mirrors Properties of Light Refractive Surgery Calculations Imaging Cataract Surgery Spherical Lenses Refraction by the Eye 2. Calculations What is the optical power (D) of a convex spherical lens with a focal length of 25 cm? +2.50D -4.00D +4.00D -2.50D None 3. Calculations Transpose the -4.00 DS/ -3.00 DC X 45 into positive cylinder notation? −5.50 DS/ +3.00 DCx45 −5.50 DS/ +3.00 DCx135 −7.00 DS/ +3.00 DCx45 −7.00 DS/ +3.00 DCx135 None 4. Calculations A hypermetrope whose glasses contain +5.00 DS lenses wants to wear contact lenses. What is the dioptric power of the contact lens that he would require? (Back vertex distance = 15 mm) + 5.4 dioptres + 5.8 dioptres - 5.0 dioptres +4.5 dioptres None 5. Calculations A crown glass prism in air has an apical angle of 4 degrees. What will the approximate angle of deviation be in the position of minimum deviation? 4 degrees 2 degrees 16 degrees 8 degrees None 6. Calculations A glass prism (refractive index 1.5) of 20 prism diopters deviates an incident of ray of light through? 20 degrees 10 degrees 5 degrees 40 degrees None 7. Calculations The spherical equivalent of a lens with power +3.00DS/-2.00 DC is? -0.50 DS +1.00 DS -1.00 DS +2.00 DS None 8. Calculations Transpose +2.00 DS/ -1.00 DC x 180 to the base curve -2.00 D? +4.00 DS/ (-2.00 DC x 90/-3.00 DC x 180) +4.00 DS/ (-2.00 DC x 90/-1.00 DC x 180) +4.00 DS/ (-2.00 DC x 90/+1.00 DC x 180) +4.00 DS/ (-3.00 DC x 90/-3.00 DC x 180) None 9. Calculations What is the magnification of a loupe of power +16 diopters? x 64 x 8 x 32 x 4 None 10. Calculations An eye has axial length 23.0mm, with average keratometry readings of 42 diopters. Using the SRK formula (constant 118.9), aiming for emmetropia, the calculated power of an intraocular lens implant would be: 23.30 D 24.30 D 24.60 D 23.60 D None 11. Calculations What is the dioptric lens power of simple magnifying glass (loupe) with a magnification of 2.5x? 10 dioptres 2.5 dioptres 25 dioptres 4 dioptres None 12. Calculations What is the accommodative power required for a myope with a -1.5 dioptre prescription to read unaided at 25 cm? 2.5 dioptre 5.5 dioptre 7 dioptre 1 dioptre None 13. Calculations What magnitude of accommodation will be required for a hypermetropic patient within +2 dioptre prescription to read unaided at 20cm? 5 dioptres 3 dioptres 7 dioptres 10 dioptres None 14. Calculations A patient's prescription is +2.00 DS/ -1.00 DC axis 180. What is the topic transposition of this to the base curve -4.00 D? +6.00 DS/ (-4.00 DC x 180/-1.00 DC x 90) +6.00 DS/ (-4.00 DC x 90/-5.00 DC x 180) +1.00 DS/ (+1.00 DC x 90/-5.00 DC x 180) +1.00 DS/ (-5.00 DC x 180/+1.00 DC x 90) None 15. Calculations What is the degree of magnification when viewing the funds of a patient with 10 dioptres of myopia with a direct ophthalmoscope? x 12.5 x 2.5 x 15 x 17.5 None 16. Calculations What is the lens to object working distance of a simple magnifying glass of 2.5 x magnifications? 20 cm 10 cm 5 cm 2.5 cm None 17. Calculations Which of the following transpositions is incorrect? +2.00/ -3.25 x 20 = +1.25/ +3.25 x 110 -3.75/ -1.75 x 80 = -5.50/ +1.75 x 170 -1.75/ -1.25 x 60 = -3.00/ +1.25 x 150 +4.50/ -2.25 x 140 = +2.25/ +2.25 x 50 None 18. Calculations A +4.00D spectacle lens is decentered 5 mm nasally. What type of prism effect is induced? 2Δ Base In 2Δ Base Up 2Δ Base Out No prism is induced None 19. Calculations What is the tube length of an astronomical telescope with a +4.00D objective lens and a +10.00D eyepiece lens 20 cm 15 cm 35 cm 30 cm None 20. Calculations What is the prismatic effect (prism dioptres) of a 4 dioptre lens that has been decanted by 30 mm? 30 0.75 12 120 None 21. Calculations An object is placed 50cm in front of a concave spherical mirror with a radius of curvature of 2.0m. What image is produced? Virtual, enlarged Real, enlarged Real, diminished Virtual, diminished None 22. Calculations What is the Brewster angle when light travels from air to glass (n= 1.50)? 41.8 56.3 65.7 47.6 None 23. Calculations How much does a 15Δ prism bend light, in degrees? 15 degrees 12.4 degrees 7.5 degrees 8.53 degrees None 24. Calculations What is the critical angle for light travelling from glass (n=1.50) to air? 47.6 degrees 65.7 degrees 56.7 degrees 41.8 degrees None 25. Calculations Convert the following spectacle prescription from plus-cylinder to minus-cylinder notation: +2.00 / +1.50 × 90 +3.50 / -1.50 × 180 +3.50 / -1.50 × 90 +0.50 / -1.50 × 180 +2.00 / -1.50 × 180 None 26. Calculations If a cornea has an anterior radius of curvature of 7.7 mm, a posterior radius of curvature of 6.8 mm, and a centre of thickness of 0.5 mm, what will its dioptric power be if it is submerged in water? Assume index of refraction of water =1.333; index of refraction of cornea = 1.376; index of refraction of aqueous = 1.336 +32.00 D +37.60 D -0.30 D -5.89 D None 27. Calculations A cyclopegic refraction is performed for on a non verbal, adult patient at a testing distance of 67 cm. The results for the right eye is as follows: +3D share neutralises the reflex when the streak is horizontal (180 degrees); +4D sphere neutralises the reflex when the streak is vertical ( 90 degrees). What is the refraction of the right eye? +1.50 (sphere) - 1.00 x90 +3.00 (sphere) + 1.00 x90 +3.00 (sphere) - 1.00 x90 +1.50 (sphere) + 1.00 x90 None 28. Calculations During cataract surgery on a patient with an eye of axial length of 23 mm, it becomes necessary to change the IOL type. The A constant for the original IOL is 118.4 and will give a bower of 21.5 dioptres. The A constant for the new IOL is 117.4. What is the power of the new IOL? 22.5 dioptres 21.0 dioptres 20.5 dioptres 22.0 dioptres None 29. Calculations An object is placed 50cm in front of a concave spherical mirror with a radius of curvature of 2.0m. What is the transverse magnification of the image? x4 x2 x3 x1 None 30. Calculations At 20 feet, the smallest letters that a child;d can read is the 20/60 line. You have the child walk towards the eye chart. How far does she walk before she can see the 20/20 line? 13 feet 15 feet 5 feet 7 feet None 31. Calculations What is the maximum amplitude of accommodation of an emmetropic patient with a near point of 20 cm? 10 dioptres 2 dioptres 5 dioptres 8 dioptres None 32. Calculations Using this instrument with a +13D lens where is the image 0.08 cm behind the lens 8 cm behind the lens 0.08 cm in front of the lens 8 cm in front of the lens None 33. Calculations An object is placed 50cm in front of a concave spherical mirror with a radius of curvature of 2.0m. What is the power of the mirror? +1.00 +2.00 -1.00 -2.00 None 34. Calculations If a 10 dioptre concave lens is decentered by 2cm temporally, this will result in a: 5 prism dioptre base-out prism 5 prism dioptre base-in prism 20 prism dioptre base-out prism 20 prism dioptre base-in prism None 35. Calculations What is the spherical equivalent of -3.50/+1.50 axis 70? -2.00/-1.50 axis 110 -2.00 DS -5.00 DS -2.75 DS None 36. Calculations During cataract surgery a complication occurs and the decision is made to place the intraocular lens (IOL) in sulcus. A 23.5 diopter IOOL has been planned for placement in the capsular bag. Which of the following lens powers is most appropriate for placement in the sulcus? 21.50 dioptre 25.5 dioptre 22.50 dioptre 24.5 dioptre None 37. Mirrors Which type of mirror is commonly used in car rearview mirrors? Plane mirror Convex mirror Parabolic mirror Concave mirror None 38. Mirrors What optical principle allows a kaleidoscope to form symmetrical patterns? Dispersion Chromatic aberration Diffraction Total internal reflection None 39. Mirrors The object lies outside the centre of curvature of a concave mirror. How is the image formed by the mirror best best described? Virtual erect diminished Real inverted enlarged Virtual erect enlarged Real inverted diminished None 40. Mirrors How does a two-way mirror work? It acts as a polarizer, allowing only certain wavelengths through. It reflects all light from both sides equally. It transmits light in one direction while reflecting most light from the other. It refracts light instead of reflecting it. None 41. Mirrors An object is placed between the center of curvature (C) and the focal point (F) of a concave mirror. What will be the characteristics of the image formed? No image is formed Real, inverted, and diminished Real, inverted, and enlarged Virtual, erect, and enlarged None 42. Mirrors When an object is placed at the focal point (F) of a concave mirror, what is the most likely outcome? A real, inverted, and magnified image is formed. A real, erect, and same-sized image is formed No image is formed because the reflected rays are parallel. A virtual, erect, and diminished image is formed. None 43. Mirrors Which of the following statements is true about the image formed by a concave mirror when the object is placed between the focal point (F) and the mirror? The image is virtual, erect, and magnified No image is formed because light rays do not reflect. The image is real, inverted, and diminished The image is real, erect, and the same size as the object. None 44. Mirrors An object is placed beyond the center of curvature (C) of a concave mirror. What will be the characteristics of the image formed? No image is formed Virtual, erect, and magnified Real, inverted, and diminished Real, erect, and enlarged None 45. Mirrors The image formed by a convex mirror is least likely to be? Virtual Diminished Lateral Inverted Erect None 46. Mirrors Which of the following is least likely to describe the image formed when an object is placed between the focal point (F) and the mirror in a concave mirror? Erect Virtual Inverted Enlarged None 47. Mirrors Which of the following is most likely a correct rule when constructing ray diagrams for a concave mirror? All of the above. A ray traveling parallel to the principal axis reflects through the focal point (F). A ray passing through the center of curvature (C) reflects back along the same path. A ray passing through the focal point (F) reflects parallel to the principal axis. None 48. Mirrors An object located between the centre of curvature and the principle focus of a concave mirror is most likely? Virtual Erect Diminished Real None 49. Mirrors Which of the following is least likely to describe the image formed when an object is placed beyond the center of curvature (C) in a concave mirror? Diminished Real Inverted Magnified None 50. Aberrations Which optical aberration is most affected when a lens is tilted? Spherical aberration Coma Chromatic aberration Pincushion distortion None 51. Aberrations Which statement about mydriasis is least likely? There is an increased depth of field There is an increase in spherical aberration There is an increase in the Stiles-Crawford effect There is decreased diffraction of light None 52. Aberrations Which lens material has the lowest chromatic aberration? High-index plastic Polycarbonate Trivex Crown Glass None 53. Aberrations Which type of optical aberration is characterized by different focal points for different wavelengths of light? Chromatic aberration Coma Spherical aberration Astigmatism None 54. Aberrations Which of the following statements about dispersion and chromatic aberration is most likely? In the human eye, blue rays focus behind red rays Red print appears nearer than blue print when both are displayed against a black background Blue-blocking and red-blocking sunglasses improve sharpness by eliminating part of the chromatic interval, thereby reducing chromatic abberation Image sharpness is improved by chromatic aberration in the eyes of the patients with achromatopsia None 55. Aberrations Coma aberration is most commonly seen in which type of optical system? Off-axis point sources High-index lenses On-axis point sources Cylindrical lenses None 56. Aberrations Which is least likely to reduce spherical aberration? Pantoscopic tilt Aplanatic surfaces Use of stops Use of a doublet None 57. Aberrations Which of the following adaptations of the eye does not reduce spherical aberration at the retina? Variable refractive index within lens Vitreous at the posterior lens surface acting as a doublet lens Graduated corneal curvature Iris position None 58. Aberrations Which of the following lens types is most likely to cause chromatic aberration? Single-element lenses made of low-dispersion glass Convex lens with high refractive index Lenses with a large aperture and a wide field of view Bifocal lenses with spherical curvature None 59. Aberrations What is the typical effect of spherical aberration in optical lenses? Light rays from the center and edges of the lens focus at different points Light rays passing through the optical center are deflected outward The lens magnifies objects excessively at the center Color fringing occurs around the edges of the image None 60. Visual Function Which of the following is least likely a test of stereoacuity Pelli-Robson Frisby TNO Titmus None 61. Visual Function Which of the following is true about LogMar? A logMAR of 0 is equal to a Snellen score of 6/60 The letter spacing is equal to one letter width The number of letters increases as you move down the chart A LogMAR of +1 is equal to Snellen score of 6/6 None 62. Visual Function Which of the following charts can be used to assess visual acuity in a child less than 1 years old? LogMAR Keeler cards Kay pictures Sheridan Gardner None 63. Visual Function Which of the following is false about LogMAR? There are five letters on each line The letter size increases in 0..1 LogMAR steps he row spacing is equal to the height of a letter from the row below Each letter can be assigned a score of 0.01 None 64. Visual Function What is the visual acuity of a newborn? 6/60 6/18-6/6 6/200-6/60 6/24 None 65. Visual Function What visual angle is subtentendedu by a letter on the 6/6 line of a snellen chart at 6cm? 5 minutes of arc 5 seconds of arc 1 second of arc 1 minute of arc None 66. Visual Function Colour vision is tested using? TNO Cardiff Ishihara N-type None 67. Visual Function Which of the following is used to tests the visual acuity of an 18-month-old child? Cardiff cards LogMAR Kay pictures Sheridan-Gardiner None 68. Visual Function Which of the following is least likely regarding functional vision loss? Optokinetic nystagmus is absent Tunnel vision is seen Normal pupil with no RAPD Presentation is with decreased visual acuity and is more common in females None 69. Visual Function Which of the following is least likely a test of stereo acuity? Cardiff cards Titmus Frisby worth 4-dot None 70. Visual Function Which of the following tests sensory function? Prisms Titmus Bagolini glasses TNO None 71. Visual Function Which of the following tests does not asses colour vision? Ishihara Farnsworth-Munsell Pelli-Robson Hardy-Rand-Rittler None 72. Visual Function A snellen visual acuity of 20/20 is equivalent to which of the following logMAR values? 0.02 10.00 0.00 1.00 None 73. Prisms Which of the the following is least likely regarding the visual image formed by a prism? Diminished Erect Displaced towards the apex Virtual None 74. Prisms A prism deviates light by 5 cm at a distance of 1 meter. What is its prismatic power? 50 prism diopters 10 prism diopters 5 prism diopters 0.5 prism diopters None 75. Prisms Which of the following is least likely to use prisms in spectacle correction? Correction of vertical diplopia Correction of horizontal diplopia Treatment of presbyopia Treatment of 6th nerve palsy None 76. Prisms In vision therapy, prisms are most commonly used to treat which of the following conditions? Hyperopia Strabismus Astigmatism None 77. Prisms Which is most likely about the image formed by a prism? It is real and displaced towards the base It is virtual and displaced towards the base It is virtual and displaced toward the apex It is real and displaced towards the apex None 78. Prisms Which of the following least likely determines the angle of deviation of a ray of light when refracted by a prism? Refractive index of the material of which the prism is made Wavelength of light of the incident ray Refracting angle of the prism Angle of incidence of the ray None 79. Prisms One prism diopter corresponds to a deviation of how many centimeters at a distance of one meter? 5 cm 2 cm 1 cm 0.5 cm None 80. Prisms In the treatment of binocular vision disorders, what effect does using prisms in spectacles typically have on the image? It shifts the image to aid fusion It causes the image to appear doubled It reduces the field of vision It enlarges the image significantly None 81. Prisms Which of the following prisms causes 180 degrees deviation with no left-to-right transposition? Wollaston prism Dove prism Fresnel prism Porro prism None 82. Prisms Which prism causes inversion of the image without deviation or lateral transposition? Dove prism Wollaston prism Porro prism Fresnel prism None 83. Prisms Which of the following statements regarding the Prentice position is least likely? The deviation of light is greater in the Prentice position than in the position of minimum deviation The incident ray is normal to one surface of the prism Glass prisms are traditionally held in the prentice position The angle of incidence equals the angle of emergence None 84. Refraction by the Eye What is the average dioptric power of an aphakic eye? 58 22 19 43 None 85. Refraction by the Eye When does the eye reach its maximum axial length? Does not stop growing 13-18 years old 1-3 years old 3-7 years old None 86. Refraction by the Eye Which most likely describes the far point of the non-accommodated -4.00D myopic eye? The far point is 25cm posterior to the eye The far point is 20cm anterior to the eye The far point and fovea are conjugate points, , The far point is nearer to the eye than is the point of focus of the fully accommodated eye. None 87. Refraction by the Eye What is the size of the adult eye? 17 mm 34 mm 24 mm 28 mm None 88. Refraction by the Eye What is the refractive index of the cornea? 1.40 1.33 1.37 1.52 None 89. Refraction by the Eye What is the radius of curvature (in mm) of the anterior surface of the cornea? 6.8 mm 5.7 mm 7.7 mm 7.0 mm None 90. Refraction by the Eye What is the total approximate refractive power of the human eye? 30D 20D 43D 60D None 91. Refraction by the Eye What is the primary cause of myopia? Weak accommodation Reduced corneal curvature Corneal irregularity Excessive axial length None 92. Refraction by the Eye What is the average axial length of an emmetropic human eye? 20 mm 22 mm 24 mm 26 mm None 93. Refraction by the Eye Which of the following best describes emmetropia? Light focuses in front of the retina without accommodation Light is scattered throughout the eye without a focal point Light focuses behind the retina without accommodation Light focuses exactly on the retina without accommodation None 94. Refraction by the Eye What happens to the eyes during the accommodative reflex? Divergence, miosis, and lens flattening Convergence, miosis, and increased lens curvature Convergence, mydriasis, and lens flattening Divergence, mydriasis, and increased lens curvature None 95. Refraction by the Eye Approximately how much of the eye's total refractive power comes from the cornea? 25% 43D 60D 10% None 96. Refraction by the Eye Which of the following is NOT part of the near triad response? Miosis Mydriasis Accommodation Convergence None 97. Refraction by the Eye A patient with an axial length of 26.5 mm is likely to have: Presbyopia Myopia Hyperopia Emmetropia None 98. Refraction by the Eye Which statement about the optical power of an infant’s eye is true? It has a lower refractive power than an adult’s eye It has fully developed accommodation at birth It is hyperopic due to a short axial length It always has a myopic refractive error None 99. Refraction by the Eye Which lens type is best suited for patients with high myopia (-10.00D and above)? Standard plastic lenses Plus lenses Bifocal lenses Aspheric high-index lenses None 100. Refraction by the Eye Which of the following is true about hyperopia (farsightedness)? It requires concave lenses for correction Light focuses in front of the retina The patient may accommodate to compensate for mild hyperopia It is associated with excessive axial length None 101. Refraction by the Eye Which of the following best describes the process of emmetropization? The gradual loss of accommodation with age The process of correcting refractive errors using spectacles or contact lenses The eye's ability to focus light using accommodation The active adjustment of the eye’s axial length and refractive components during development None 102. Refraction by the Eye Why does the cornea provide more refractive power than the lens? It has a greater curvature. It has a higher refractive index. It is thicker than the lens. It is closer to the retina. None 103. Refraction by the Eye Which previous model is Gullstrand's reduced eye a refinement of? Helmholtz Schooner Kepler Krunenberg None 104. Refraction by the Eye Based on Gullstrand's reduced eye, which of the following points is 7.08mm behind the anterior corneal surface? Principle point First focal point Nodal point Second focal point None 105. Refraction by the Eye In Gullstrand's reduced eye the, how far is the anterior focal point from the anterior cornea? 15.7 cm 17.7 mm 17.7 cm 15.7 mm None 106. Refraction by the Eye The total refractive power of Gullstrand's reduced eye when relaxed is? +58.64 diopter +60.64 diopter +50.64 diopter +55.64 diopter None 107. Refraction by the Eye Which of the following is not proven to slow myopic progression? Using reading glasses Outdoor activity Using atropine None of the above None 108. Refraction by the Eye The most likely effective power of the crystalline lens in situ is? 23 diopters 37 diopters 43 diopters 15 diopter None 109. Refraction by the Eye In a hypermetropic eye, moving a convex lens away from the eye? The effectivity of the lens is unchanged The effectivity of the lens is increased None of the above The effectivity of the lens is decreased None 110. Refraction by the Eye Which is is least likely to be true? The dioptric power of the accommodated eye is called its static refraction The range of accommodation is the distance between the far point and near point The near point at which an object can be clearly seen when maximum accommodation is used The amplitude of accommodation is the dioptric power difference between the eye at rest and when full accommodated None 111. Refraction by the Eye Which ocular structure has the highest refractive power? Cornea Lens Aqueous humour Vitreous humour None 112. Refraction by the Eye Which of the following is true about the lens? The anterior suture gas inverted Y shape The posterior suture has an inverted Y shape The lens becomes more spherical when looking at the distance The posterior capsule thins with age None 113. Refraction by the Eye A high AC/A ratio is most likely associated with? Convergence weakness Divergence excess esotropia Convergence excess exotropia Convergence excess esotropia None 114. Instruments Which optical instrument provides an upright and non-reversed image of the retina? Goldman contact lens + slit lamp Direct ophthalmoscope Hruby lens Indirect ophthalmoscope + 20D lens None 115. Instruments Which one of the following statements about the Geneva lens measure is true? It is possible to deduce the total power of a thin lens by measuring both surface powers and calculating the difference between them When placed on a convex surface the central pin is extended relative to the peripheral pins It uses three spring-loaded pins to measure the surface curvature of a lens It is calibrated for the refractive index of crown glass None 116. Instruments Which optical instrument provides an inverted and reversed image of the retina? Hruby lens Indirect ophthalmoscope + 20D lens Direct ophthalmoscope Goldman contact lens + slit lamp None 117. Instruments Looking through the inferior mirror of a Zeiss 4 mirror goniolensm you see a foreign body at 7 o'clock. Where is this foreign body in your patient? 7 O'Clock 11 O'Clock 5 O'Clock 1 O'Clock None 118. Instruments What factor would reduce your field of view when examining a patient with this instrument: A Large pupil size Hyperopic patient Moving closer to the patient Myopic patient None 119. Instruments Which of the following instruments relies on total internal reflection? Operating microscope Gonioscopy lens Fibre-optic intracular illumination system Direct ophthalmoscope None 120. Instruments Which Volk examination lenses has an image magnification factor of 0.93? 78 dioptre 60 dioptre 66 dioptre 90 dioptre None 121. Instruments Using the following instrument, your image would be: 9 DD (Disc Diameters) Real Inverted x20 magnified None 122. Instruments You examine a patient with the following instrument. Which factor affects your image size: Size of pupil Patient's refractive state Illumination Distance from patient None 123. Instruments Which type of patient cannot be examined using the following instrument: Aphakic Hyperopic Myopic Astigmatic None 124. Instruments Using this instrument how can you enhance your view of the posterior pole in a myopic patient? Use a narrow beam Use a green filter Ask them to keep their glasses on Stand further away from the patient None 125. Instruments Using this instrument how could you enhance your view of a micro-aneurysm? Use a narrow beam Move away from the patient Use a red filter Remove a myopic patients glasses None 126. Instruments The image formed by this instrument is not: Inverted Magnified Real Between the patient and the condensing lens None 127. Instruments What is the field of view achieved with this instrument? 60 degrees 10 degrees 25 degrees 50 degrees None 128. Instruments Your field of illumination is restricted by what when using this instrument? Hyperopic observer Hyperopic patient A small pupil Using a condensing None 129. Instruments Which of the following is true regarding indirect ophthalmoscopy? A +20D concave lens is required The field of illumination is largest in myopia The image is virtual The image is erect None 130. Instruments Your field of view is restricted by what when using this instrument? large patient's pupil size Large observer's pupil size Small patient's pupil size Small observer's pupil size None 131. Instruments You move the condensing lens away from a patient whilst using this instrument. You notice that this causes the image size to increases. This means the patient is: Emmetropic Hyperopic Moving their head Myopic None 132. Instruments You move the condensing lens away from a patient whilst using this instrument. You notice that the image size gets smaller. This means the patient is: Poorly dilated Hyperopic Myopic Emmetropic None 133. Instruments Which one of the following statements about the Hruby lens is incorrect? It is used with its concave surface towards the observer It has a power of -58.6 dioptres The retinal image formed is virtual, erect and diminished The retinal image formed lies within the eye of the patient None 134. Instruments which of the following indirect ophthalmoscopy lens gives the sides field of view? 15, 20, 28 , 30 d 28 D 30d 20 D 15 D None 135. Instruments Which of the following phenomenon is used in optical fibre? Total Internal Reflection Diffraction Refraction Scattering None 136. Imaging In fluorescein fungus imaging which colour is the excitation filter? Blue Yellow Red Green None 137. Imaging Which of the following properties of light is used by the scanning laser polarimeter to measure nerve fibre layer thickness? Power level Pulse duration Focal spot size Polarization None 138. Imaging A patient purchases a pair of yellow sunglasses. Which colour will be hardest to see? Green Yellow Blue Red None 139. Imaging Which of the following components is part of an optical coherence tomography (OCT) system? Double pinhole Split prism Beam splitter Laser light source None 140. Imaging In fluorescein fungus imaging which colour is the barrier filter? Yellow Red Blue Green None 141. Imaging What is the optical principle behind fundus autofluorescence imaging in retinal disease diagnosis? Reflection of blue light from the inner retina Fluorescence emission from lipofuscin in the retinal pigment epithelium Light scattering from retinal nerve fiber layers Absorption of infrared light to highlight choroidal structures None 142. Imaging Which type of light is used in Optical Coherence Tomography (OCT)? Infrared X-rays Microwave Ultraviolet None 143. Imaging Optical Coherence Tomography (OCT) primarily utilizes which principle to obtain high-resolution images of the retina? Interference Diffraction Fluorescence Refraction None 144. Imaging Which of the following best describes fluorescence in ophthalmic imaging? Reflection of light at the same wavelength Scattering of light in all directions Light absorption at one wavelength and emission at a longer wavelength Complete absorption of light without re-emission None 145. Lasers Which of the following light wavelengths can cause photokeratitis? Infrared X rays Visible light Ultraviolet, None 146. Lasers Which of the following is absorbed by haemoglobin and melanin only? Diode laser Frequency-doubled ND:YAG PRP Argon blue-green None 147. Lasers Ophthalmic lasers are under which laser safety class? 3a-3b 2 1-2 3b-4 None 148. Lasers which laser causes it principle effect through photo disruption? Argon laser Eximer laser Cyclodiode laser Nd-YAG laser None 149. Lasers Which laser causes it principle effect through photoablation? Nd-YAG laser Cyclodiode laser Eximer laser Argon laser None 150. Lasers Which of the following characteristics is a property of all ophthalmic lasers? High efficiency Stimulated emission Continuous wave operation A plasma active medium None 151. Lasers Which ophthalmic laser primarily causes its principal effect through photocoagulation? Nd-YAG laser Argon laser Eximer laser Femtosecond laser None 152. Lasers The ability of light wave from a laser to form interference fringes with another wave from the same beam, separated in time, is a measure of its? Spatial coherence Temporal coherence Directionality Intensity None 153. Lasers What is the primary mechanism of the femtosecond laser in cataract surgery? Photocoagulation Photoablation Thermal coagulation Photodisruption None 154. Lasers Which laser emits light at a wavelength of 1064 nm? Excimer laser Nd:YAG laser Diode laser Argon laser None 155. Lasers Which laser is commonly used for selective laser trabeculoplasty (SLT) in open-angle glaucoma? Diode laser Argon laser Nd:YAG laser Excimer laser None 156. Lasers Which laser is primarily used for panretinal photocoagulation (PRP) in diabetic retinopathy? Excimer laser Nd:YAG laser Femtosecond laser Argon laser None 157. Lasers During retinal photocoagulation, which mechanism primarily leads to therapeutic tissue effects? Photoablation Photochemical reaction Photodisruption Photothermal reaction None 158. Lasers Which optical principle is primarily responsible for the effect of laser photocoagulation in retinal surgery? Dispersion of light within the vitreous to induce therapeutic heating Reflection of laser light causing retinal coagulation Absorption of laser energy leading to a photothermal effect Refractive focusing of the laser to create a photomechanical disruption None 159. Cataract Surgery How do accommodating IOLs attempt to restore dynamic near vision? Utilize a pinhole effect to improve near vision Change curvature dynamically to alter refractive power Split light into multiple focal points for simultaneous viewing Shift anteriorly and posteriorly in response to ciliary muscle contraction None 160. Cataract Surgery Which of the following statements correctly describes the relationship between IOL power, axial length and corneal power? The IOL power should increase as the power of the cornea increases and axial length increases The IOL power should increase as the power of the cornea decreases and axial length decreases The IOL power should ncrease as the power of the cornea decreases and axial length increases The IOL power should increase as the power of the cornea increases and axial length decreases None 161. Cataract Surgery Why is no anterior chamber depth (ACD) measurement used in the SRK equation? Modern IOLs are all designed to have the same AC The SRK was designed to eliminate the need for ACD Postoperative ACD is not necessarily the same as preoperative ACD Regression analysis did not show increased accuracy when ACD was included in the SRK formula None 162. Cataract Surgery Which laser is commonly used for posterior capsulotomy after cataract surgery? Nd:YAG laser Excimer laser Femtosecond laser Argon laser None 163. Cataract Surgery Which parameter is least likely to be needed to calculate IOL power before cataract surgery? Central corneal thickness Preoperative refraction Amount of LASIK treatment Postoperative topography measurements None 164. Cataract Surgery Which value is not required in the SRK formula for intraocular lens calculation? A-constant for the desired IOL Axial length Average keratometry reading Anterior chamber depth None 165. Cataract Surgery In a patient with LASIK, which change introduces the most error in the IOL calculations? Anterior chamber depth Axial length Corneal curvature measurements High-order aberrations None 166. Cataract Surgery Which optical phenomenon is most commonly affected by the presence of a cataract? Reduction in axial length, leading to myopic shift Enhanced night vision due to lens opacification Increased light scatter and decreased contrast sensitivity Improved near vision due to reduced corneal astigmatism None 167. Cataract Surgery What optical property of ultrasound waves is essential for phacoemulsification? Chromatic dispersion separates nuclear layers for better emulsification High-frequency sound waves induce cavitation and lens fragmentation Infrared absorption creates controlled thermal energy to emulsify the lens Refraction of light waves within the lens nucleus enhances fragmentation None 168. Cataract Surgery Which optical change is commonly observed after cataract removal? Myopic shift due to corneal steepening Hyperopic shift due to loss of the crystalline lens power Increased astigmatism from irregular corneal wound healing Reduced intraocular light scatter and improved night vision None 169. Cataract Surgery How do multifocal IOLs provide both near and distance vision correction? They induce higher-order aberrations that compensate for presbyopia They dynamically change curvature based on pupil size They selectively absorb short wavelengths to enhance near focus They use diffractive optics to split incoming light into multiple focal points None 170. Cataract Surgery What optical principle allows monovision cataract surgery to provide both near and distance vision? Increasing corneal curvature in one eye to mimic accommodation Utilizing polarized light filters within IOLs to enhance focus Adjusting pupil dynamics to selectively refract light Creating anisometropia by implanting different-powered IOLs in each eye None 171. Cataract Surgery Why do patients with large pupils often struggle with multifocal IOLs? Reduced contrast sensitivity due to corneal light scatter Increased exposure to out-of-focus light rays, causing glare and halos Loss of peripheral vision from excessive pupil dilation Enhanced near vision at the expense of distance vision None 172. Cataract Surgery What is the most critical factor when implanting a toric IOL for astigmatism correction? Precise alignment of the IOL axis to match the patient's astigmatic axis Selecting an IOL with a lower refractive index to minimize distortion Increasing corneal hydration to reduce astigmatic impact Ensuring a higher-powered spherical IOL to compensate for residual cylinder None 173. Cataract Surgery How does small incision cataract surgery (SICS) impact postoperative corneal astigmatism? Increases irregular astigmatism due to unpredictable corneal wound healing Induces myopic shift due to decreased corneal thickness Reduces corneal astigmatism by minimizing incision-induced changes Shifts the astigmatic axis to a more oblique orientation None 174. Cataract Surgery Why are some intraocular lenses designed to filter blue light? To improve dark adaptation by blocking peripheral scatter To reduce phototoxic damage to the retina and improve contrast sensitivity To decrease pupil constriction and increase retinal illumination To enhance near vision by selectively focusing shorter wavelengths None 175. Cataract Surgery How do Extended Depth of Focus (EDOF) intraocular lenses achieve a continuous range of vision? Increased asphericity to induce controlled spherical aberrations Use of chromatic aberration correction to extend focal points Elimination of multiple focal points to create a single elongated focus Pinhole optics to minimize out-of-focus blur None 176. Cataract Surgery Why might a surgeon implant a secondary (piggyback) IOL in a pseudophakic patient? To improve depth perception in monovision patients To reduce spherical aberrations caused by the first IOL To compensate for posterior capsule opacification To correct significant residual refractive error None 177. Cataract Surgery Which optical phenomenon is most likely to affect visual quality in patients with small pupils after multifocal IOL implantation? Increased chromatic aberration due to pupil-dependent refraction Reduced effect of multifocal optics leading to poor near vision Widening of peripheral field with loss of central clarity Increased depth of focus but reduced contrast sensitivity None 178. Cataract Surgery Why are negative-power IOLs sometimes required for extremely high myopia in cataract surgery? Negative lenses enhance retinal image magnification in myopic patients A posteriorly placed IOL requires negative power for proper light convergence The natural crystalline lens has strong positive power, and its removal necessitates a negative correction Negative lenses compensate for elongated axial length by neutralizing corneal power None 179. Cataract Surgery What optical aberration is most commonly induced when an IOL is significantly decentered postoperatively? Chromatic aberration Coma Barrel distortion Spherical aberration None 180. Cataract Surgery How does reverse optic capture influence refractive outcomes in IOL implantation? Pushes the IOL posteriorly to induce a hyperopic shift Increases posterior capsule opacification by trapping lens fibers Minimizes glare and halos by reducing light scatter at the IOL edge Reduces higher-order aberrations by stabilizing the IOL None 181. Cataract Surgery What optical principle contributes to positive dysphotopsia in some IOL patients? Excessive chromatic dispersion from multifocal optics Light scattering due to incomplete posterior capsule opacification Internal reflection of light at the IOL edge Pupil-dependent refraction misalignment None 182. Refractive Surgery Which of the following is not a complication of refractive eye surgery? Glare PCO DLK Dry eyes None 183. Refractive Surgery How long should soft contact lenses be withheld for before undergoing laser eye surgery? 7-14 days 28-35 days 14-21 days 21-28 days None 184. Refractive Surgery A corneal flap is created, the storm is then ablated, and the flap is replaced. what is this a description of? YAG laser capsulotomy LASEK LASIK PRK None 185. Refractive Surgery Which of the following is not an intervention for myopic correction? Negative diopter lens Central corneal ablation with LASIK Peripheral corneal ablation with LASIK Central corneal ablation with LASEK None 186. Refractive Surgery Which of the following is a key difference between PRK and LASIK? PRK does not require a corneal flap LASIK has a slower visual recovery than PRK PRK removes less corneal tissue than LASIK LASIK has a higher risk of corneal haze None 187. Refractive Surgery Which of the following is a contraindication for LASIK surgery? History of dry eyes Keratoconus Presbyopia A) Mild myopia (-2.00D) None 188. Refractive Surgery Why might a phakic IOL (ICL) be preferred over LASIK in some patients? LASIK is the only option for high myopia LASIK is more effective Phakic IOLs preserve the cornea Phakic IOLs are only used in presbyopia None 189. Refractive Surgery What is the primary advantage of SMILE (Small Incision Lenticule Extraction) over LASIK? No need for a femtosecond laser Less risk of dry eye Faster recovery Better correction of hyperopia None 190. Refractive Surgery Which instrument is the most accurate for measuring anterior chamber depth? Slit lamp with Van Herick technique Direct ophthalmoscope Pentacam (Scheimpflug imaging) Indirect ophthalmoscope None 191. Refractive Surgery Why are IOL power calculations more challenging in post-LASIK patients? The effective lens position is unpredictable due to changes in corneal biomechanics The axial length is affected by previous refractive surgery Corneal power is inaccurately estimated due to altered curvature The residual epithelial thickness alters the refractive index of the cornea None 192. Retinal Surgery Which optical phenomenon contributes to improved visualization of the retina during surgery under a microscope? Enhancement of retinal contrast via polarized light filtering Total internal reflection at the vitreous-retinal interface Reduction of spherical aberration using coaxial illumination Light scattering due to small pupil size None 193. Retinal Surgery Silicone oil in aphakic eye leads to? No change Myopic shift Hyperopic shift Blindess None 194. Retinal Surgery Why are wide-angle viewing systems preferred in modern retinal surgery? They magnify the central retina, allowing for more detailed surgical precision They increase image brightness by eliminating reflections from the corneal surface They provide a panoramic view of the peripheral retina without requiring frequent lens adjustments They reduce chromatic aberration and enhance color contrast in retinal structures None 195. Retinal Surgery Which optical property makes perfluorocarbon liquids (PFCL) useful in vitreoretinal surgery? High viscosity, preventing intraoperative turbulence Low refractive index, improving light transmission through the vitreous High specific gravity allowing mechanical flattening of the retina Selective absorption of short-wavelength light, reducing phototoxicity None 196. Retinal Surgery Which refractive change is commonly observed following pars plana vitrectomy with gas tamponade? Myopic shift Astigmatic shift Hyperopic shift No significant refractive change None 197. Retinal Surgery Which optical aberration is most commonly encountered when performing wide-field retinal imaging? Coma from off-axis light sources Spherical aberration from excessive lens curvature Distortion due to peripheral magnification differences Chromatic aberration from lens dispersion None 198. Retinal Surgery What optical principle makes endoillumination essential for vitreoretinal surgery? High refractive index of fiber optics ensures focused light delivery Total internal reflection of fiber-optic light enhances contrast Polarization reduces glare and enhances macular detail Scattering within the vitreous helps illuminate deep retinal layers None 199. Prescriptions Which bifocal segment design provides the widest near reading area? Round-segment bifocal Executive bifocal Flat-top bifocal Progressive lens None 200. Prescriptions Which of the following is an advantage of soft contact lenses over RGP lenses? Higher oxygen permeability More effective in correcting keratoconus Lower risk of corneal infections Better initial comfort None 201. Prescriptions An adult has diplopia and a left hypertrophic of 6Δ. which combination of prisms in his glasses will most likely align the two images for him? 6Δ base down (OD), nothing (OS) 4Δ base down (OD), 2Δ base down (OS) 3Δ base up(OD), 3Δ base down (OS) 3Δ base down (OD), 3Δ base up (OS) None 202. Prescriptions Which test is commonly used to measure the amplitude of accommodation? Bagolini striated lenses Push-up test Worth 4-dot test Maddox rod test None 203. Prescriptions What type of image distortion is most common with high-plus (hyperopic) lenses? Coma Pincushion distortion Barrel distortion Chromatic aberration None 204. Prescriptions What strength of lens is needed so that a patient with 20/160 visual acuity can read newsprint without accommodation? +12.50 D +8.00 D +5.00 D +10.00 D None 205. Prescriptions Which aberration is reduced by using aspheric lenses? Coma Chromatic aberration Distortion Spherical aberration None 206. Prescriptions A Maddox rod is place in front of a patient's right eye with its axis vertical. She is asked to look at a white spot and sees a horizontal red line with the light above it. What does that indicate? Exophoria Right hypophoria Right hyperphoria Esophoria None 207. Prescriptions You use the duochrome test to refine the refraction of a patient. The patient says the red letter are much clearer than the green. The patient is: Astigmatic Anisometropic Overminused Overplussed None 208. Prescriptions Which optical issue do progressive lenses correct that bifocals do not? High astigmatism Near vision Distance vision Intermediate vision None 209. Prescriptions What is the primary purpose of the Jackson Cross Cylinder (JCC) test? To determine near addition power To assess accommodation ability To measure spherical refractive error To refine the axis and power of astigmatism None 210. Prescriptions What type of patient benefits the most from myodisc lenses? Astigmatism Presbyopia High myopia High hyperopia None 211. Prescriptions What is the primary purpose of an anti-reflective coating on eyeglass lenses? To prevent all light from entering the eye To increase light reflection for better contrast To reduce glare and ghost images To create a mirror effect on the lens surface None 212. Prescriptions The base curve of a contact lens is primarily chosen based on which measurement? Central keratometry readings Pupil size Anterior chamber depth Lens diameter None 213. Prescriptions What is a key advantage of Fresnel prisms in ophthalmic use? They provide higher magnification. They do not require refraction correction. They reduce chromatic aberration. They are lightweight and flexible. None 214. Prescriptions Which function of the tear film is most critical for successful contact lens wear? Removing debris from the eye Maintaining corneal hydration Creating a smooth optical surface Providing nutrients to the cornea None 215. Prescriptions What is unique about gradient index (GRIN) lenses compared to standard lenses? They work only for concave lenses. They have a uniform refractive index throughout the material. They can only be used in microscopes. They have a continuously varying refractive index. None 216. Prescriptions In clinical practice, a Maddox rod is used to assess which of the following? Visual acuity Intraocular pressure Color vision Ocular alignment None 217. Prescriptions How does increasing the base curve radius affect a contact lens fit? It loosens the lens fit. It has no effect on fit. It increases the lens power. It tightens the lens fit. None 218. Prescriptions What is the primary effect of high-minus spectacle lenses on retinal image size? It induces a prismatic shift. It has no effect on image size. It reduces image size. It increases magnification. None 219. Prescriptions Which type of spherical lens is used to correct myopia? Convex (converging) lens Plano-convex lens Concave (diverging) lens Cylindrical lens None 220. Prescriptions Which optical phenomenon may cause double vision when a prism is incorrectly placed in spectacles? Ghosting Image displacement Monocular diplopia Chromatic aberration None 221. Prescriptions How does a pinhole improve vision in a hyperopic patient? It magnifies the image. It increases depth of focus by reducing peripheral blur. It increases the corneal curvature. It increases accommodation. None 222. Prescriptions What is the primary purpose of a retinoscope in clinical practice? To visualize the anterior chamber To assess intraocular pressure To measure refractive error objectively To examine the retina None 223. Prescriptions Which type of contact lens is most commonly used to correct aphakia? Hybrid lens with aspheric optics Scleral lens High-plus silicone hydrogel soft lens Rigid gas-permeable (RGP) corneal lens None 224. Prescriptions Which of the following is a correct transcription of a 0.50 Jackson's Cross cylinder? +0.25 DS/ -0.25 DC +0.25 DS/ -0.50 DC +0.50 DS/ -0.25 DC +0.50 DS/ -0.50 DC None 225. Prescriptions Regarding the Jackson's cross cylinder? The cylinder in the cross cylinder has twice the power of the sphere The cross cylinder's handle is held in line with the axis of the trial cylinder The handle is traditionally in line with the axis of the negative cylinder It is equivalent to two superimposed cylindrical lenses with axes at 45 degrees to each other None 226. Prescriptions Which is least likely in spectacle correction for aphakia? Ring scotoma Pin fusion distortion Image magnification Barrel distortion None 227. Prescriptions Which of the following regarding contact lenses is used in patients with dry eyes? Monthly lenses Silicone hydrogel Soft lenses Rigid lenses None 228. Prescriptions A patient is fitted with a rigid gas permeable contact lens. The average K reading is 7.67mm, and the base curve of the lens in 7.5 mm. What is the shape of the resultant tear lens? Plano No tear lens will be formed Convex Concave None 229. Prescriptions In a myopic patient, which of the following is increased with contact lens wear compared to glasses? Image distortion Image magnification Optical aberrations Aniseikonia None 230. Prescriptions Which of the following statement is correct regarding the segment choice when prescribing bifocals for a patient with hyperopia? The use of a round-top segment reduces the prismatic displacement effect and increases image jump The practitioner should leave the choice of the segment type to the optician, A flat-top segment is preferred because of its thin upper edge which causes less prismatic effect A round-top segment is preferred because it lessens image jump None 231. Prescriptions A patient with a red Maddox rod with the cylinders orientated horizontally placed over her left eye. What does she see when she views a distant white fixation light? Red light, horizontal red line Red light, vertical red line White light, vertical red line White light, horizontal red line None 232. Astigmatism Which of the following is an advantage of rigid gas permeable (RGP) contact lenses over soft lenses? Reduced risk of corneal hypoxia Greater initial comfort Higher oxygen permeability Does not require lens care None 233. Astigmatism Which type of lens is used to correct astigmatism? Plano-convex lens Prism lens Cylindrical lens Spherical lens None 234. Astigmatism In against-the-rule (ATR) astigmatism, the steepest meridian is located at approximately: 180° 135° 45° 90° None 235. Astigmatism In simple myopic astigmatism, how does light focus? One focal point is on the retina, and the other is behind the retina. Both focal points are in front of the retina. Both focal points are behind the retina. One focal point is on the retina, and the other is in front of the retina. None 236. Astigmatism What type of astigmatism is more commonly seen in older adults? Irregular astigmatism Oblique astigmatism Against-the-rule astigmatism With-the-rule astigmatism None 237. Astigmatism In a cylindrical lens, where does the full power of the lens act? Perpendicular to the axis Along the axis At 45° to the axis Evenly across the entire lens None 238. Astigmatism In a patient with regular astigmatism, how are the principal meridians positioned? Perpendicular to each other Randomly aligned Parallel to each other At 30-degree intervals None 239. Astigmatism Where does a cylindrical lens exert its refractive power? Along the axis of the lens Perpendicular to the axis of the lens At the center of the lens Equally across the entire lens None 240. Astigmatism A patient’s vision improves with a stenopaic slit placed at 90°. What type of refractive error does this suggest? Against-the-rule astigmatism Simple hyperopia With-the-rule astigmatism Simple myopia None 241. Astigmatism Which of the following is used to manage keratoconus? LASEK Rigid contact Lenses Toric lenses LASIK None 242. Astigmatism In simple hypermetropic astigmatism? The focal lines are straddling the retina One focal line is on the retina whilst the other is behind it Both focal lines are in front of the retina Both focal lines are behind the retina None 243. Astigmatism Which of the following prescriptions is an example of 'with the rule' astigmatism? -5.25 DS/ +2.50 DC axis 180 +3.50 DS/ -0.75 DC axis 90 -1.50 DS/ -1.00 DC axis 45 +3.00 DS/ +2.25 DC axis 85 None 244. Astigmatism Keratoconus most likely causes? Axial myopia Axial hypermetropia Refractive myopia Refractive hypermetropia None 245. Astigmatism If rays of light from all meridians come into focus behind the retina, this is called? Simple hypermetropic astigmatism Simple myopic astigmatism Compound hypermetropic astigmatism Compound myopic astigmatism None 246. Low Vision Aids Which low vision aid can help a patient with Age Related Macular Degeneration watch TV? Magnifying glass Galilean telescope Hubble telescope loop magnifiers None 247. Low Vision Aids What is the primary purpose of low vision aids in the management of patients with visual impairment? To magnify images for clearer vision To treat underlying eye diseases To restore normal vision To eliminate the need for corrective lenses None 248. Low Vision Aids Which of the following low vision aids is best suited for improving distance vision in individuals with low vision? Magnification spectacles Bifocal lenses Reading glasses Telescopic lenses None 249. Low Vision Aids Which of the following low vision aids is most commonly used for close-up tasks such as reading? Telescopic lenses Fresnel prisms High-powered magnifying glasses Visual field expanders None 250. Low Vision Aids Which of the following statements about the Galilean telescope is least likely? It has an extremely narrow field of view The image is typically dimmer than seen with the unaided eye It is composed of two convex lenses The objective and eye piece lenses are separated by the difference between their focal lengths None 251. Low Vision Aids What role do prisms play in binoculars? They increase the brightness of the image. They invert and erect the image. They reduce chromatic aberration. They allow light to be focused at a single point. None 252. Low Vision Aids Which of the following best describes the image produced by a Galilean telescope? Virtual, inverted, magnified, at the sum of the focal lengths of the object and eyepiece lens Virtual, erect, magnified, at the sum of the focal lengths of the objective and eyepiece lens Virtual, erect, magnified at infinity Virtual, inverted, magnified, at infinity None 253. Low Vision Aids Which optical application commonly uses a plano-convex lens? Magnifying glass Myopia correction Optical fiber focusing Camera telephoto lens None 254. Clinical Which of the following is not associated with myopia? RRD Uveal effusion syndrome ROP Congenital glaucoma None 255. Clinical Which of the following is used to distinguish between open and closed angle glaucoma? Fundoscopy Perimetry Gonioscopy Tonometry None 256. Clinical What investigation is used to measure corneal curvature? Pachymetry Tonometry Keratometry Perimetry None 257. Clinical A patient with presbyopia says he can now see without his reading glasses, Which cataract does the patient have? Posterior subcapsular Anterior subcapsular Nuclear sclerotic Cortical None 258. Clinical Which of the following structures is affected leading to presbyopia? Zonules Iris Lens Cornea None 259. Clinical Which of the following factors increases the risk of infection in a patient using extended wear contact lenses? Exposure to smoke Intact corneal epithelium Switching to daily -wear contacts Normal eyelid function None 260. Clinical Regarding the prevalence of myopia (of at least -0.5 dioptres): It is high in white Europeans compared to other ethnicities Myopis tends to decrease with nuclear sclerosis of the lens It is lower in adults than in young children Time spent outdoors as a child is a protective factor agains myopia None 261. Clinical A child has a cycloplegia refraction 0D +6.00D, OS +2.00. What is the best way to manage the anisometropia? Occlusion therapy Partial correction Full correction Paleoptic therapy None 262. Clinical Which lens can be used to examine the anterior chamber angle? 90D lens Three mirror lens Wide field lens Hruby lens None 263. Clinical Which of the following indirect ophthalmoscopy lenses gives the greater magnification? 20 D 30 D 28 D 15 D None 264. Clinical How does corneal edema primarily affect vision? Enhances contrast sensitivity Causes hyperopia Increases light scatter Induces myopia None 265. Clinical Which of the following is a common optical correction for presbyopia? Plano convex lenses Progressive addition lenses (PALs) Single-vision myopic glasses Cylindrical lenses None 266. Clinical What is the primary cause of presbyopia? Corneal steepening Weakening of the extraocular muscles Loss of lens elasticity Increase in axial length None 267. Clinical Which factor is least likely to influence the onset of presbyopia? Age Gender Geographic location Refractive error None 268. Spherical Lenses How is the image formed by a convex lens of an object located inside the first focal point best described? Erect, real, inside age second focal point, diminished Inverted, virtual, at infinity, diminished Inverted, real, outside the second focal point, magnified Erect, virtual, further from lens than object, magnified None 269. Spherical Lenses What role does a concave lens play in a Keplerian telescope? It increases the field of view while maintaining image size It enhances color contrast by removing chromatic aberration It corrects the inverted image formed by the convex objective lens It magnifies the image without altering the focal length None 270. Spherical Lenses For a convex lens, placing an object outside the first principle focus results in an image that is Magnified, inverted, virtual Erect, real Enlarged, erect, virtual Inverted, real None 271. Spherical Lenses A higher refractive index lens has which of the following advantages? Increased spherical aberrations Reduced lens thickness Increased lens thickness Increased chromatic aberration None 272. Spherical Lenses The image formed by a thin concave lens is? Real, inverted, magnified, outside the second focal point Real erect, magnified, further from the lens than the object Virtual, inverted, diminished at infinity Virtual, erect, diminished, inside the second focal point None 273. Spherical Lenses Tilting a spherical lens can induce which type of optical effect? Induced prism Reduced power No effect Elimination of aberrations None 274. Spherical Lenses What happens when the curvature of a spherical lens increases? The refractive index of the lens material changes The focal length decreases, making the lens more powerful The lens starts to behave like a prism instead of a spherical lens The focal length increases, reducing the lens’s optical power None 275. Spherical Lenses Which factor increases the optical power of a spherical lens, assuming the shape remains the same? Using a material with a higher refractive index Decreasing the thickness of the lens Reducing the curvature of the lens surfaces Increasing the focal length of the lens None 276. Spherical Lenses What type of image is always produced by a concave (diverging) spherical lens? Virtual, inverted, and same size as the object Real, upright, and larger than the object Virtual, upright, and smaller than the object Real, inverted, and magnified None 277. Spherical Lenses Which factor increases the optical power of a spherical lens, assuming the shape remains the same? Increasing the focal length of the lens Decreasing the thickness of the lens Reducing the curvature of the lens surfaces Using a material with a higher refractive index None 278. Spherical Lenses Which statement is true regarding the difference between a biconcave and a plano-concave lens? A plano-concave lens is used to converge light rays A plano-concave lens has equal power on both sides A biconcave lens forms only real images A biconcave lens has two concave surfaces and more negative power None 279. Spherical Lenses What happens to the focal length of a convex lens when it is submerged in water? It depends only on the lens curvature, not the surrounding medium It remains the same because focal length is a material property It increases because the refractive index contrast between the lens and water is reduced It decreases because water enhances light bending None 280. Jokes 😉 Why do people randomly test themselves for color blindness online? Because it’s a convenient way to procrastinate at work. Because they need to know whether they’d survive as a bomb defuser in an action movie. Because they want to prove their friends wrong in an argument about "blue or green?" Because they saw a meme that convinced them they’ve been colorblind their whole life. None 281. Jokes 😉 What’s the real reason optometrists get excited about astigmatism? Because they secretly enjoy watching patients struggle with JCC testing. Because saying “with-the-rule astigmatism” makes them feel fancy. Because prescribing cylindrical correction makes them feel like wizards. Because it’s a good excuse to show off their maths skills. None 282. Jokes 😉 What is the most common reaction after LASIK surgery? “Wow, I can see! Time to read the fine print on my medical bills.” “Can I get a refund if I still need glasses?” “My vision is so clear, I can now see all my life mistakes.” “So… I paid thousands of dollars and now I have dry eyes forever?” None 283. Properties of Light A beam of light passes from air into glass at an angle. What happens to its frequency? It becomes zero. It increases. It decreases. It remains the same. None 284. Properties of Light Which of the following is least likely to happen when constructing a correct ray diagram? Rays that do not intersect will eventually converge if extended. If the rays appear to diverge, a virtual image is formed. At least two rays are required to locate an image. The image forms where the reflected or refracted rays intersect. None 285. Properties of Light Destructive interference is most likely in: Corneal epithelium Refraction Corneal endothelium Antireflective lens coatings None 286. Properties of Light When light moves from air to water and travels towards the normal at the interface, which of the following is more likely to happen? The light will not bend at all. The light will undergo total internal reflection. The light will bend away from the normal The light will bend towards the normal. None 287. Properties of Light Which statement about the speed of light is correct? Light travels fastest in water. Light slows down when entering a denser medium. Light travels at the same speed in all mediums. Light speeds up when entering a denser medium. None 288. Properties of Light Which of the following terms best describes a substance which only allows the transmission of light in an incident plane aligned with its structure, by absorbing other light waves? Mirrored Scattering Dichroic birefringent None 289. Properties of Light Which of the following is most likely the correct rule for drawing a principal ray in a concave mirror ray diagram? A ray incident at the mirror surface always travels straight without reflection. A ray passing through the centre of curvature (C) reflects at a random angle. A ray passing through the focal point (F) reflects parallel to the principal axis. A ray parallel to the principal axis reflects through the center of curvature (C). None 290. Properties of Light Which change is most likely when a ray of light passes into a denser medium? Frequency and plane Velocity and frequency Velocity only Velocity and plane None 291. Properties of Light Which definition most likely describes radiant flux? The intensity if light emitted from a source The amount of light falling in a surface The amount of light emitted from a source The amount of light reflected from a surface None 292. Properties of Light The image of an object formed by reflection at a plane surface is least likely to be? Erect Laterally inverted Diminished Virtual None 293. Properties of Light How is surface illumination related to the distance from the light source? Directly proportional Directly proportional to the square root Inversely proportional Inversely proportional the square root None 294. Properties of Light Regarding optical radiation, which of the following is least likely? Light emitted through fluorescence typically has a longer wavelength than the excitation light that trigger it The wavelength of light decreases as it enters a transparent material from a vacuum Shorter wavelengths undergo increased scatter The energy of a photon is directly proportional to its wavelength None 295. Properties of Light What causes the appearance of a secondary rainbow? Diffraction of light waves A different type of water droplet composition A change in the sun’s intensity Multiple internal reflections inside raindrops None 296. Properties of Light Wavelength is best defined as? The maximum displacement of an imaginary particle on the wave from the baseline Any portion of the cycle The distance between two symmetrical parts of the wave motion One complete oscillation None 297. Properties of Light What type of reflection occurs on a rough surface? Diffuse reflection Polarized reflection Specular reflection Total internal reflection None 298. Properties of Light What does polarized light consist of? Light waves oscillating in multiple planes Light waves oscillating in a single plane Light waves with reduced intensity Light waves with equal wavelengths None 299. Properties of Light Total internal reflection occurs is most likely if the incident ray strikes the interface of media at? The critical angle An angle greater than the critical angle An angle less than the critical angle 90 degrees None 300. Properties of Light The most likely unit of illuminance is? Watts per steradian Cadelas (lumen per steradian) Lux (human per square metre) Lumen None 301. Properties of Light Which catastrophic image is most likely to form an inverted image? Add description here! Posterior lens surface Anterior corneal surface Anterior lens surface Posterior corneal surface None 302. Properties of Light Which type of light wave carries the most energy? Infrared light Ultraviolet light Red light Blue light None 303. Properties of Light Which of the following statements about convave lenses is TRUE? They cause light to diverge They are used to correct myopia They always produce virtual images They converge parallel light rays to a focal point None 304. Properties of Light Which of the following correctly describes light? It is a longitudinal wave. It requires a medium to travel. It can exhibit both wave and particle properties. It travels at the same speed in all materials. None 305. Properties of Light Which of the following factors affects the scattering of light in the eye? Wavelength of light Intraocular pressure Corneal thickness Lens elasticity None 306. Properties of Light What is the main law governing the reflection of light? Law of Equal Angles Snell’s Law Brewster’s Law Fermat’s Principle None 307. Properties of Light What happens to light as it moves from a less dense medium (air) to a denser medium (cornea)? It remains unaltered It bends away from the normal It slows down and bends toward the normal It speeds up None 308. Properties of Light Which of the following pairs is matched correctly? Prism diopter-meters per centimetre Dioptre-meter Refractive index-meters per second Wavelength-nanometers None 309. Properties of Light Which of the following statements about convex lenses is TRUE? They cause light to diverge They are used to correct myopia They converge parallel light rays to a focal point They always produce virtual images None 310. Properties of Light Which optical principle explains the formation of mirages? Dispersion Reflection Refraction Diffraction None 311. Properties of Light Which color of visible light has the shortest wavelength? Red Yellow Green Blue None 312. Properties of Light When the angle of incidence is greater than the critical angle? The angle of incidence cannot be greater than the critical angle Total Internal reflection occurs Total external refraction occurs Reflection mostly occurs with some refraction None Please fill in the comment box below. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time's up
April 15 2025 Histopathology Ryian mohamed 0 1. Cornea Which layer of the cornea contains keratocytes? Epithelium Bowman's layer Stroma Descemet’s membrane Endothelium None 2. Retina The internal limiting membrane of the retina is formed by: Müller cell footplates Astrocytes Photoreceptor nuclei Retinal pigment epithelium Ganglion cells None 3. Retina Drusen are histopathological features seen in: Diabetic retinopathy Retinitis pigmentosa Age-related macular degeneration Uveitis Retinoblastoma None 4. Cornea The primary site of lesion in keratoconus is: Epithelium Bowman's layer Stroma Descemet's membrane Endothelium None 5. Pathology Rosette formations on histopathology are characteristic of: Retinoblastoma Conjunctival lymphoma Orbital cellulitis Choroidal nevus None 6. Cornea Which structure is acellular and acts as the basement membrane for the corneal endothelium? Stroma Bowman's layer Descemet's membrane Bruch’s membrane Internal limiting membrane None 7. Pathology Fuchs endothelial dystrophy primarily affects which corneal layer? Epithelium Stroma Endothelium Bowman's layer Limbus None 8. Pathology Psammoma bodies may be seen in histology of which orbital tumor? Cavernous hemangioma Optic nerve glioma Schwannoma Meningioma Rhabdomyosarcoma None 9. Eyelids Which type of gland is the Meibomian gland classified as? Apocrine Sebaceous Eccrine Endocrine Mucous None 10. Retina Which retinal layer contains the nuclei of photoreceptor cells? Inner nuclear layer Outer nuclear layer Ganglion cell layer Outer plexiform layer Retinal pigment epithelium None Time's up
March 18 2025 Optics Ryian mohamed 0 Welcome to Optics 😉 Name Email 1. Please select your category: Please select your answer Lasers Retinal Surgery Jokes Astigmatism Instruments Low Vision Aids Clinical Visual Function Aberrations Prescriptions Prisms Mirrors Properties of Light Refractive Surgery Calculations Imaging Cataract Surgery Spherical Lenses Refraction by the Eye 2. Calculations What is the optical power (D) of a convex spherical lens with a focal length of 25 cm? +2.50D -4.00D +4.00D -2.50D None 3. Calculations Transpose the -4.00 DS/ -3.00 DC X 45 into positive cylinder notation? −5.50 DS/ +3.00 DCx45 −5.50 DS/ +3.00 DCx135 −7.00 DS/ +3.00 DCx45 −7.00 DS/ +3.00 DCx135 None 4. Calculations A hypermetrope whose glasses contain +5.00 DS lenses wants to wear contact lenses. What is the dioptric power of the contact lens that he would require? (Back vertex distance = 15 mm) + 5.4 dioptres + 5.8 dioptres - 5.0 dioptres +4.5 dioptres None 5. Calculations A crown glass prism in air has an apical angle of 4 degrees. What will the approximate angle of deviation be in the position of minimum deviation? 4 degrees 2 degrees 16 degrees 8 degrees None 6. Calculations A glass prism (refractive index 1.5) of 20 prism diopters deviates an incident of ray of light through? 20 degrees 10 degrees 5 degrees 40 degrees None 7. Calculations The spherical equivalent of a lens with power +3.00DS/-2.00 DC is? -0.50 DS +1.00 DS -1.00 DS +2.00 DS None 8. Calculations Transpose +2.00 DS/ -1.00 DC x 180 to the base curve -2.00 D? +4.00 DS/ (-2.00 DC x 90/-3.00 DC x 180) +4.00 DS/ (-2.00 DC x 90/-1.00 DC x 180) +4.00 DS/ (-2.00 DC x 90/+1.00 DC x 180) +4.00 DS/ (-3.00 DC x 90/-3.00 DC x 180) None 9. Calculations What is the magnification of a loupe of power +16 diopters? x 64 x 8 x 32 x 4 None 10. Calculations An eye has axial length 23.0mm, with average keratometry readings of 42 diopters. Using the SRK formula (constant 118.9), aiming for emmetropia, the calculated power of an intraocular lens implant would be: 23.30 D 24.30 D 24.60 D 23.60 D None 11. Calculations What is the dioptric lens power of simple magnifying glass (loupe) with a magnification of 2.5x? 10 dioptres 2.5 dioptres 25 dioptres 4 dioptres None 12. Calculations What is the accommodative power required for a myope with a -1.5 dioptre prescription to read unaided at 25 cm? 2.5 dioptre 5.5 dioptre 7 dioptre 1 dioptre None 13. Calculations What magnitude of accommodation will be required for a hypermetropic patient within +2 dioptre prescription to read unaided at 20cm? 5 dioptres 3 dioptres 7 dioptres 10 dioptres None 14. Calculations A patient's prescription is +2.00 DS/ -1.00 DC axis 180. What is the topic transposition of this to the base curve -4.00 D? +6.00 DS/ (-4.00 DC x 180/-1.00 DC x 90) +6.00 DS/ (-4.00 DC x 90/-5.00 DC x 180) +1.00 DS/ (+1.00 DC x 90/-5.00 DC x 180) +1.00 DS/ (-5.00 DC x 180/+1.00 DC x 90) None 15. Calculations What is the degree of magnification when viewing the funds of a patient with 10 dioptres of myopia with a direct ophthalmoscope? x 12.5 x 2.5 x 15 x 17.5 None 16. Calculations What is the lens to object working distance of a simple magnifying glass of 2.5 x magnifications? 20 cm 10 cm 5 cm 2.5 cm None 17. Calculations Which of the following transpositions is incorrect? +2.00/ -3.25 x 20 = +1.25/ +3.25 x 110 -3.75/ -1.75 x 80 = -5.50/ +1.75 x 170 -1.75/ -1.25 x 60 = -3.00/ +1.25 x 150 +4.50/ -2.25 x 140 = +2.25/ +2.25 x 50 None 18. Calculations A +4.00D spectacle lens is decentered 5 mm nasally. What type of prism effect is induced? 2Δ Base In 2Δ Base Up 2Δ Base Out No prism is induced None 19. Calculations What is the tube length of an astronomical telescope with a +4.00D objective lens and a +10.00D eyepiece lens 20 cm 15 cm 35 cm 30 cm None 20. Calculations What is the prismatic effect (prism dioptres) of a 4 dioptre lens that has been decanted by 30 mm? 30 0.75 12 120 None 21. Calculations An object is placed 50cm in front of a concave spherical mirror with a radius of curvature of 2.0m. What image is produced? Virtual, enlarged Real, enlarged Real, diminished Virtual, diminished None 22. Calculations What is the Brewster angle when light travels from air to glass (n= 1.50)? 41.8 56.3 65.7 47.6 None 23. Calculations How much does a 15Δ prism bend light, in degrees? 15 degrees 12.4 degrees 7.5 degrees 8.53 degrees None 24. Calculations What is the critical angle for light travelling from glass (n=1.50) to air? 47.6 degrees 65.7 degrees 56.7 degrees 41.8 degrees None 25. Calculations Convert the following spectacle prescription from plus-cylinder to minus-cylinder notation: +2.00 / +1.50 × 90 +3.50 / -1.50 × 180 +3.50 / -1.50 × 90 +0.50 / -1.50 × 180 +2.00 / -1.50 × 180 None 26. Calculations If a cornea has an anterior radius of curvature of 7.7 mm, a posterior radius of curvature of 6.8 mm, and a centre of thickness of 0.5 mm, what will its dioptric power be if it is submerged in water? Assume index of refraction of water =1.333; index of refraction of cornea = 1.376; index of refraction of aqueous = 1.336 +32.00 D +37.60 D -0.30 D -5.89 D None 27. Calculations A cyclopegic refraction is performed for on a non verbal, adult patient at a testing distance of 67 cm. The results for the right eye is as follows: +3D share neutralises the reflex when the streak is horizontal (180 degrees); +4D sphere neutralises the reflex when the streak is vertical ( 90 degrees). What is the refraction of the right eye? +1.50 (sphere) - 1.00 x90 +3.00 (sphere) + 1.00 x90 +3.00 (sphere) - 1.00 x90 +1.50 (sphere) + 1.00 x90 None 28. Calculations During cataract surgery on a patient with an eye of axial length of 23 mm, it becomes necessary to change the IOL type. The A constant for the original IOL is 118.4 and will give a bower of 21.5 dioptres. The A constant for the new IOL is 117.4. What is the power of the new IOL? 22.5 dioptres 21.0 dioptres 20.5 dioptres 22.0 dioptres None 29. Calculations An object is placed 50cm in front of a concave spherical mirror with a radius of curvature of 2.0m. What is the transverse magnification of the image? x4 x2 x3 x1 None 30. Calculations At 20 feet, the smallest letters that a child;d can read is the 20/60 line. You have the child walk towards the eye chart. How far does she walk before she can see the 20/20 line? 13 feet 15 feet 5 feet 7 feet None 31. Calculations What is the maximum amplitude of accommodation of an emmetropic patient with a near point of 20 cm? 10 dioptres 2 dioptres 5 dioptres 8 dioptres None 32. Calculations Using this instrument with a +13D lens where is the image 0.08 cm behind the lens 8 cm behind the lens 0.08 cm in front of the lens 8 cm in front of the lens None 33. Calculations An object is placed 50cm in front of a concave spherical mirror with a radius of curvature of 2.0m. What is the power of the mirror? +1.00 +2.00 -1.00 -2.00 None 34. Calculations If a 10 dioptre concave lens is decentered by 2cm temporally, this will result in a: 5 prism dioptre base-out prism 5 prism dioptre base-in prism 20 prism dioptre base-out prism 20 prism dioptre base-in prism None 35. Calculations What is the spherical equivalent of -3.50/+1.50 axis 70? -2.00/-1.50 axis 110 -2.00 DS -5.00 DS -2.75 DS None 36. Calculations During cataract surgery a complication occurs and the decision is made to place the intraocular lens (IOL) in sulcus. A 23.5 diopter IOOL has been planned for placement in the capsular bag. Which of the following lens powers is most appropriate for placement in the sulcus? 21.50 dioptre 25.5 dioptre 22.50 dioptre 24.5 dioptre None 37. Mirrors Which type of mirror is commonly used in car rearview mirrors? Plane mirror Convex mirror Parabolic mirror Concave mirror None 38. Mirrors What optical principle allows a kaleidoscope to form symmetrical patterns? Dispersion Chromatic aberration Diffraction Total internal reflection None 39. Mirrors The object lies outside the centre of curvature of a concave mirror. How is the image formed by the mirror best best described? Virtual erect diminished Real inverted enlarged Virtual erect enlarged Real inverted diminished None 40. Mirrors How does a two-way mirror work? It acts as a polarizer, allowing only certain wavelengths through. It reflects all light from both sides equally. It transmits light in one direction while reflecting most light from the other. It refracts light instead of reflecting it. None 41. Mirrors An object is placed between the center of curvature (C) and the focal point (F) of a concave mirror. What will be the characteristics of the image formed? No image is formed Real, inverted, and diminished Real, inverted, and enlarged Virtual, erect, and enlarged None 42. Mirrors When an object is placed at the focal point (F) of a concave mirror, what is the most likely outcome? A real, inverted, and magnified image is formed. A real, erect, and same-sized image is formed No image is formed because the reflected rays are parallel. A virtual, erect, and diminished image is formed. None 43. Mirrors Which of the following statements is true about the image formed by a concave mirror when the object is placed between the focal point (F) and the mirror? The image is virtual, erect, and magnified No image is formed because light rays do not reflect. The image is real, inverted, and diminished The image is real, erect, and the same size as the object. None 44. Mirrors An object is placed beyond the center of curvature (C) of a concave mirror. What will be the characteristics of the image formed? No image is formed Virtual, erect, and magnified Real, inverted, and diminished Real, erect, and enlarged None 45. Mirrors The image formed by a convex mirror is least likely to be? Virtual Diminished Lateral Inverted Erect None 46. Mirrors Which of the following is least likely to describe the image formed when an object is placed between the focal point (F) and the mirror in a concave mirror? Erect Virtual Inverted Enlarged None 47. Mirrors Which of the following is most likely a correct rule when constructing ray diagrams for a concave mirror? All of the above. A ray traveling parallel to the principal axis reflects through the focal point (F). A ray passing through the center of curvature (C) reflects back along the same path. A ray passing through the focal point (F) reflects parallel to the principal axis. None 48. Mirrors An object located between the centre of curvature and the principle focus of a concave mirror is most likely? Virtual Erect Diminished Real None 49. Mirrors Which of the following is least likely to describe the image formed when an object is placed beyond the center of curvature (C) in a concave mirror? Diminished Real Inverted Magnified None 50. Aberrations Which optical aberration is most affected when a lens is tilted? Spherical aberration Coma Chromatic aberration Pincushion distortion None 51. Aberrations Which statement about mydriasis is least likely? There is an increased depth of field There is an increase in spherical aberration There is an increase in the Stiles-Crawford effect There is decreased diffraction of light None 52. Aberrations Which lens material has the lowest chromatic aberration? High-index plastic Polycarbonate Trivex Crown Glass None 53. Aberrations Which type of optical aberration is characterized by different focal points for different wavelengths of light? Chromatic aberration Coma Spherical aberration Astigmatism None 54. Aberrations Which of the following statements about dispersion and chromatic aberration is most likely? In the human eye, blue rays focus behind red rays Red print appears nearer than blue print when both are displayed against a black background Blue-blocking and red-blocking sunglasses improve sharpness by eliminating part of the chromatic interval, thereby reducing chromatic abberation Image sharpness is improved by chromatic aberration in the eyes of the patients with achromatopsia None 55. Aberrations Coma aberration is most commonly seen in which type of optical system? Off-axis point sources High-index lenses On-axis point sources Cylindrical lenses None 56. Aberrations Which is least likely to reduce spherical aberration? Pantoscopic tilt Aplanatic surfaces Use of stops Use of a doublet None 57. Aberrations Which of the following adaptations of the eye does not reduce spherical aberration at the retina? Variable refractive index within lens Vitreous at the posterior lens surface acting as a doublet lens Graduated corneal curvature Iris position None 58. Aberrations Which of the following lens types is most likely to cause chromatic aberration? Single-element lenses made of low-dispersion glass Convex lens with high refractive index Lenses with a large aperture and a wide field of view Bifocal lenses with spherical curvature None 59. Aberrations What is the typical effect of spherical aberration in optical lenses? Light rays from the center and edges of the lens focus at different points Light rays passing through the optical center are deflected outward The lens magnifies objects excessively at the center Color fringing occurs around the edges of the image None 60. Visual Function Which of the following is least likely a test of stereoacuity Pelli-Robson Frisby TNO Titmus None 61. Visual Function Which of the following is true about LogMar? A logMAR of 0 is equal to a Snellen score of 6/60 The letter spacing is equal to one letter width The number of letters increases as you move down the chart A LogMAR of +1 is equal to Snellen score of 6/6 None 62. Visual Function Which of the following charts can be used to assess visual acuity in a child less than 1 years old? LogMAR Keeler cards Kay pictures Sheridan Gardner None 63. Visual Function Which of the following is false about LogMAR? There are five letters on each line The letter size increases in 0..1 LogMAR steps he row spacing is equal to the height of a letter from the row below Each letter can be assigned a score of 0.01 None 64. Visual Function What is the visual acuity of a newborn? 6/60 6/18-6/6 6/200-6/60 6/24 None 65. Visual Function What visual angle is subtentendedu by a letter on the 6/6 line of a snellen chart at 6cm? 5 minutes of arc 5 seconds of arc 1 second of arc 1 minute of arc None 66. Visual Function Colour vision is tested using? TNO Cardiff Ishihara N-type None 67. Visual Function Which of the following is used to tests the visual acuity of an 18-month-old child? Cardiff cards LogMAR Kay pictures Sheridan-Gardiner None 68. Visual Function Which of the following is least likely regarding functional vision loss? Optokinetic nystagmus is absent Tunnel vision is seen Normal pupil with no RAPD Presentation is with decreased visual acuity and is more common in females None 69. Visual Function Which of the following is least likely a test of stereo acuity? Cardiff cards Titmus Frisby worth 4-dot None 70. Visual Function Which of the following tests sensory function? Prisms Titmus Bagolini glasses TNO None 71. Visual Function Which of the following tests does not asses colour vision? Ishihara Farnsworth-Munsell Pelli-Robson Hardy-Rand-Rittler None 72. Visual Function A snellen visual acuity of 20/20 is equivalent to which of the following logMAR values? 0.02 10.00 0.00 1.00 None 73. Prisms Which of the the following is least likely regarding the visual image formed by a prism? Diminished Erect Displaced towards the apex Virtual None 74. Prisms A prism deviates light by 5 cm at a distance of 1 meter. What is its prismatic power? 50 prism diopters 10 prism diopters 5 prism diopters 0.5 prism diopters None 75. Prisms Which of the following is least likely to use prisms in spectacle correction? Correction of vertical diplopia Correction of horizontal diplopia Treatment of presbyopia Treatment of 6th nerve palsy None 76. Prisms In vision therapy, prisms are most commonly used to treat which of the following conditions? Hyperopia Strabismus Astigmatism None 77. Prisms Which is most likely about the image formed by a prism? It is real and displaced towards the base It is virtual and displaced towards the base It is virtual and displaced toward the apex It is real and displaced towards the apex None 78. Prisms Which of the following least likely determines the angle of deviation of a ray of light when refracted by a prism? Refractive index of the material of which the prism is made Wavelength of light of the incident ray Refracting angle of the prism Angle of incidence of the ray None 79. Prisms One prism diopter corresponds to a deviation of how many centimeters at a distance of one meter? 5 cm 2 cm 1 cm 0.5 cm None 80. Prisms In the treatment of binocular vision disorders, what effect does using prisms in spectacles typically have on the image? It shifts the image to aid fusion It causes the image to appear doubled It reduces the field of vision It enlarges the image significantly None 81. Prisms Which of the following prisms causes 180 degrees deviation with no left-to-right transposition? Wollaston prism Dove prism Fresnel prism Porro prism None 82. Prisms Which prism causes inversion of the image without deviation or lateral transposition? Dove prism Wollaston prism Porro prism Fresnel prism None 83. Prisms Which of the following statements regarding the Prentice position is least likely? The deviation of light is greater in the Prentice position than in the position of minimum deviation The incident ray is normal to one surface of the prism Glass prisms are traditionally held in the prentice position The angle of incidence equals the angle of emergence None 84. Refraction by the Eye What is the average dioptric power of an aphakic eye? 58 22 19 43 None 85. Refraction by the Eye When does the eye reach its maximum axial length? Does not stop growing 13-18 years old 1-3 years old 3-7 years old None 86. Refraction by the Eye Which most likely describes the far point of the non-accommodated -4.00D myopic eye? The far point is 25cm posterior to the eye The far point is 20cm anterior to the eye The far point and fovea are conjugate points, , The far point is nearer to the eye than is the point of focus of the fully accommodated eye. None 87. Refraction by the Eye What is the size of the adult eye? 17 mm 34 mm 24 mm 28 mm None 88. Refraction by the Eye What is the refractive index of the cornea? 1.40 1.33 1.37 1.52 None 89. Refraction by the Eye What is the radius of curvature (in mm) of the anterior surface of the cornea? 6.8 mm 5.7 mm 7.7 mm 7.0 mm None 90. Refraction by the Eye What is the total approximate refractive power of the human eye? 30D 20D 43D 60D None 91. Refraction by the Eye What is the primary cause of myopia? Weak accommodation Reduced corneal curvature Corneal irregularity Excessive axial length None 92. Refraction by the Eye What is the average axial length of an emmetropic human eye? 20 mm 22 mm 24 mm 26 mm None 93. Refraction by the Eye Which of the following best describes emmetropia? Light focuses in front of the retina without accommodation Light is scattered throughout the eye without a focal point Light focuses behind the retina without accommodation Light focuses exactly on the retina without accommodation None 94. Refraction by the Eye What happens to the eyes during the accommodative reflex? Divergence, miosis, and lens flattening Convergence, miosis, and increased lens curvature Convergence, mydriasis, and lens flattening Divergence, mydriasis, and increased lens curvature None 95. Refraction by the Eye Approximately how much of the eye's total refractive power comes from the cornea? 25% 43D 60D 10% None 96. Refraction by the Eye Which of the following is NOT part of the near triad response? Miosis Mydriasis Accommodation Convergence None 97. Refraction by the Eye A patient with an axial length of 26.5 mm is likely to have: Presbyopia Myopia Hyperopia Emmetropia None 98. Refraction by the Eye Which statement about the optical power of an infant’s eye is true? It has a lower refractive power than an adult’s eye It has fully developed accommodation at birth It is hyperopic due to a short axial length It always has a myopic refractive error None 99. Refraction by the Eye Which lens type is best suited for patients with high myopia (-10.00D and above)? Standard plastic lenses Plus lenses Bifocal lenses Aspheric high-index lenses None 100. Refraction by the Eye Which of the following is true about hyperopia (farsightedness)? It requires concave lenses for correction Light focuses in front of the retina The patient may accommodate to compensate for mild hyperopia It is associated with excessive axial length None 101. Refraction by the Eye Which of the following best describes the process of emmetropization? The gradual loss of accommodation with age The process of correcting refractive errors using spectacles or contact lenses The eye's ability to focus light using accommodation The active adjustment of the eye’s axial length and refractive components during development None 102. Refraction by the Eye Why does the cornea provide more refractive power than the lens? It has a greater curvature. It has a higher refractive index. It is thicker than the lens. It is closer to the retina. None 103. Refraction by the Eye Which previous model is Gullstrand's reduced eye a refinement of? Helmholtz Schooner Kepler Krunenberg None 104. Refraction by the Eye Based on Gullstrand's reduced eye, which of the following points is 7.08mm behind the anterior corneal surface? Principle point First focal point Nodal point Second focal point None 105. Refraction by the Eye In Gullstrand's reduced eye the, how far is the anterior focal point from the anterior cornea? 15.7 cm 17.7 mm 17.7 cm 15.7 mm None 106. Refraction by the Eye The total refractive power of Gullstrand's reduced eye when relaxed is? +58.64 diopter +60.64 diopter +50.64 diopter +55.64 diopter None 107. Refraction by the Eye Which of the following is not proven to slow myopic progression? Using reading glasses Outdoor activity Using atropine None of the above None 108. Refraction by the Eye The most likely effective power of the crystalline lens in situ is? 23 diopters 37 diopters 43 diopters 15 diopter None 109. Refraction by the Eye In a hypermetropic eye, moving a convex lens away from the eye? The effectivity of the lens is unchanged The effectivity of the lens is increased None of the above The effectivity of the lens is decreased None 110. Refraction by the Eye Which is is least likely to be true? The dioptric power of the accommodated eye is called its static refraction The range of accommodation is the distance between the far point and near point The near point at which an object can be clearly seen when maximum accommodation is used The amplitude of accommodation is the dioptric power difference between the eye at rest and when full accommodated None 111. Refraction by the Eye Which ocular structure has the highest refractive power? Cornea Lens Aqueous humour Vitreous humour None 112. Refraction by the Eye Which of the following is true about the lens? The anterior suture gas inverted Y shape The posterior suture has an inverted Y shape The lens becomes more spherical when looking at the distance The posterior capsule thins with age None 113. Refraction by the Eye A high AC/A ratio is most likely associated with? Convergence weakness Divergence excess esotropia Convergence excess exotropia Convergence excess esotropia None 114. Instruments Which optical instrument provides an upright and non-reversed image of the retina? Goldman contact lens + slit lamp Direct ophthalmoscope Hruby lens Indirect ophthalmoscope + 20D lens None 115. Instruments Which one of the following statements about the Geneva lens measure is true? It is possible to deduce the total power of a thin lens by measuring both surface powers and calculating the difference between them When placed on a convex surface the central pin is extended relative to the peripheral pins It uses three spring-loaded pins to measure the surface curvature of a lens It is calibrated for the refractive index of crown glass None 116. Instruments Which optical instrument provides an inverted and reversed image of the retina? Hruby lens Indirect ophthalmoscope + 20D lens Direct ophthalmoscope Goldman contact lens + slit lamp None 117. Instruments Looking through the inferior mirror of a Zeiss 4 mirror goniolensm you see a foreign body at 7 o'clock. Where is this foreign body in your patient? 7 O'Clock 11 O'Clock 5 O'Clock 1 O'Clock None 118. Instruments What factor would reduce your field of view when examining a patient with this instrument: A Large pupil size Hyperopic patient Moving closer to the patient Myopic patient None 119. Instruments Which of the following instruments relies on total internal reflection? Operating microscope Gonioscopy lens Fibre-optic intracular illumination system Direct ophthalmoscope None 120. Instruments Which Volk examination lenses has an image magnification factor of 0.93? 78 dioptre 60 dioptre 66 dioptre 90 dioptre None 121. Instruments Using the following instrument, your image would be: 9 DD (Disc Diameters) Real Inverted x20 magnified None 122. Instruments You examine a patient with the following instrument. Which factor affects your image size: Size of pupil Patient's refractive state Illumination Distance from patient None 123. Instruments Which type of patient cannot be examined using the following instrument: Aphakic Hyperopic Myopic Astigmatic None 124. Instruments Using this instrument how can you enhance your view of the posterior pole in a myopic patient? Use a narrow beam Use a green filter Ask them to keep their glasses on Stand further away from the patient None 125. Instruments Using this instrument how could you enhance your view of a micro-aneurysm? Use a narrow beam Move away from the patient Use a red filter Remove a myopic patients glasses None 126. Instruments The image formed by this instrument is not: Inverted Magnified Real Between the patient and the condensing lens None 127. Instruments What is the field of view achieved with this instrument? 60 degrees 10 degrees 25 degrees 50 degrees None 128. Instruments Your field of illumination is restricted by what when using this instrument? Hyperopic observer Hyperopic patient A small pupil Using a condensing None 129. Instruments Which of the following is true regarding indirect ophthalmoscopy? A +20D concave lens is required The field of illumination is largest in myopia The image is virtual The image is erect None 130. Instruments Your field of view is restricted by what when using this instrument? large patient's pupil size Large observer's pupil size Small patient's pupil size Small observer's pupil size None 131. Instruments You move the condensing lens away from a patient whilst using this instrument. You notice that this causes the image size to increases. This means the patient is: Emmetropic Hyperopic Moving their head Myopic None 132. Instruments You move the condensing lens away from a patient whilst using this instrument. You notice that the image size gets smaller. This means the patient is: Poorly dilated Hyperopic Myopic Emmetropic None 133. Instruments Which one of the following statements about the Hruby lens is incorrect? It is used with its concave surface towards the observer It has a power of -58.6 dioptres The retinal image formed is virtual, erect and diminished The retinal image formed lies within the eye of the patient None 134. Instruments which of the following indirect ophthalmoscopy lens gives the sides field of view? 15, 20, 28 , 30 d 28 D 30d 20 D 15 D None 135. Instruments Which of the following phenomenon is used in optical fibre? Total Internal Reflection Diffraction Refraction Scattering None 136. Imaging In fluorescein fungus imaging which colour is the excitation filter? Blue Yellow Red Green None 137. Imaging Which of the following properties of light is used by the scanning laser polarimeter to measure nerve fibre layer thickness? Power level Pulse duration Focal spot size Polarization None 138. Imaging A patient purchases a pair of yellow sunglasses. Which colour will be hardest to see? Green Yellow Blue Red None 139. Imaging Which of the following components is part of an optical coherence tomography (OCT) system? Double pinhole Split prism Beam splitter Laser light source None 140. Imaging In fluorescein fungus imaging which colour is the barrier filter? Yellow Red Blue Green None 141. Imaging What is the optical principle behind fundus autofluorescence imaging in retinal disease diagnosis? Reflection of blue light from the inner retina Fluorescence emission from lipofuscin in the retinal pigment epithelium Light scattering from retinal nerve fiber layers Absorption of infrared light to highlight choroidal structures None 142. Imaging Which type of light is used in Optical Coherence Tomography (OCT)? Infrared X-rays Microwave Ultraviolet None 143. Imaging Optical Coherence Tomography (OCT) primarily utilizes which principle to obtain high-resolution images of the retina? Interference Diffraction Fluorescence Refraction None 144. Imaging Which of the following best describes fluorescence in ophthalmic imaging? Reflection of light at the same wavelength Scattering of light in all directions Light absorption at one wavelength and emission at a longer wavelength Complete absorption of light without re-emission None 145. Lasers Which of the following light wavelengths can cause photokeratitis? Infrared X rays Visible light Ultraviolet, None 146. Lasers Which of the following is absorbed by haemoglobin and melanin only? Diode laser Frequency-doubled ND:YAG PRP Argon blue-green None 147. Lasers Ophthalmic lasers are under which laser safety class? 3a-3b 2 1-2 3b-4 None 148. Lasers which laser causes it principle effect through photo disruption? Argon laser Eximer laser Cyclodiode laser Nd-YAG laser None 149. Lasers Which laser causes it principle effect through photoablation? Nd-YAG laser Cyclodiode laser Eximer laser Argon laser None 150. Lasers Which of the following characteristics is a property of all ophthalmic lasers? High efficiency Stimulated emission Continuous wave operation A plasma active medium None 151. Lasers Which ophthalmic laser primarily causes its principal effect through photocoagulation? Nd-YAG laser Argon laser Eximer laser Femtosecond laser None 152. Lasers The ability of light wave from a laser to form interference fringes with another wave from the same beam, separated in time, is a measure of its? Spatial coherence Temporal coherence Directionality Intensity None 153. Lasers What is the primary mechanism of the femtosecond laser in cataract surgery? Photocoagulation Photoablation Thermal coagulation Photodisruption None 154. Lasers Which laser emits light at a wavelength of 1064 nm? Excimer laser Nd:YAG laser Diode laser Argon laser None 155. Lasers Which laser is commonly used for selective laser trabeculoplasty (SLT) in open-angle glaucoma? Diode laser Argon laser Nd:YAG laser Excimer laser None 156. Lasers Which laser is primarily used for panretinal photocoagulation (PRP) in diabetic retinopathy? Excimer laser Nd:YAG laser Femtosecond laser Argon laser None 157. Lasers During retinal photocoagulation, which mechanism primarily leads to therapeutic tissue effects? Photoablation Photochemical reaction Photodisruption Photothermal reaction None 158. Lasers Which optical principle is primarily responsible for the effect of laser photocoagulation in retinal surgery? Dispersion of light within the vitreous to induce therapeutic heating Reflection of laser light causing retinal coagulation Absorption of laser energy leading to a photothermal effect Refractive focusing of the laser to create a photomechanical disruption None 159. Cataract Surgery How do accommodating IOLs attempt to restore dynamic near vision? Utilize a pinhole effect to improve near vision Change curvature dynamically to alter refractive power Split light into multiple focal points for simultaneous viewing Shift anteriorly and posteriorly in response to ciliary muscle contraction None 160. Cataract Surgery Which of the following statements correctly describes the relationship between IOL power, axial length and corneal power? The IOL power should increase as the power of the cornea increases and axial length increases The IOL power should increase as the power of the cornea decreases and axial length decreases The IOL power should ncrease as the power of the cornea decreases and axial length increases The IOL power should increase as the power of the cornea increases and axial length decreases None 161. Cataract Surgery Why is no anterior chamber depth (ACD) measurement used in the SRK equation? Modern IOLs are all designed to have the same AC The SRK was designed to eliminate the need for ACD Postoperative ACD is not necessarily the same as preoperative ACD Regression analysis did not show increased accuracy when ACD was included in the SRK formula None 162. Cataract Surgery Which laser is commonly used for posterior capsulotomy after cataract surgery? Nd:YAG laser Excimer laser Femtosecond laser Argon laser None 163. Cataract Surgery Which parameter is least likely to be needed to calculate IOL power before cataract surgery? Central corneal thickness Preoperative refraction Amount of LASIK treatment Postoperative topography measurements None 164. Cataract Surgery Which value is not required in the SRK formula for intraocular lens calculation? A-constant for the desired IOL Axial length Average keratometry reading Anterior chamber depth None 165. Cataract Surgery In a patient with LASIK, which change introduces the most error in the IOL calculations? Anterior chamber depth Axial length Corneal curvature measurements High-order aberrations None 166. Cataract Surgery Which optical phenomenon is most commonly affected by the presence of a cataract? Reduction in axial length, leading to myopic shift Enhanced night vision due to lens opacification Increased light scatter and decreased contrast sensitivity Improved near vision due to reduced corneal astigmatism None 167. Cataract Surgery What optical property of ultrasound waves is essential for phacoemulsification? Chromatic dispersion separates nuclear layers for better emulsification High-frequency sound waves induce cavitation and lens fragmentation Infrared absorption creates controlled thermal energy to emulsify the lens Refraction of light waves within the lens nucleus enhances fragmentation None 168. Cataract Surgery Which optical change is commonly observed after cataract removal? Myopic shift due to corneal steepening Hyperopic shift due to loss of the crystalline lens power Increased astigmatism from irregular corneal wound healing Reduced intraocular light scatter and improved night vision None 169. Cataract Surgery How do multifocal IOLs provide both near and distance vision correction? They induce higher-order aberrations that compensate for presbyopia They dynamically change curvature based on pupil size They selectively absorb short wavelengths to enhance near focus They use diffractive optics to split incoming light into multiple focal points None 170. Cataract Surgery What optical principle allows monovision cataract surgery to provide both near and distance vision? Increasing corneal curvature in one eye to mimic accommodation Utilizing polarized light filters within IOLs to enhance focus Adjusting pupil dynamics to selectively refract light Creating anisometropia by implanting different-powered IOLs in each eye None 171. Cataract Surgery Why do patients with large pupils often struggle with multifocal IOLs? Reduced contrast sensitivity due to corneal light scatter Increased exposure to out-of-focus light rays, causing glare and halos Loss of peripheral vision from excessive pupil dilation Enhanced near vision at the expense of distance vision None 172. Cataract Surgery What is the most critical factor when implanting a toric IOL for astigmatism correction? Precise alignment of the IOL axis to match the patient's astigmatic axis Selecting an IOL with a lower refractive index to minimize distortion Increasing corneal hydration to reduce astigmatic impact Ensuring a higher-powered spherical IOL to compensate for residual cylinder None 173. Cataract Surgery How does small incision cataract surgery (SICS) impact postoperative corneal astigmatism? Increases irregular astigmatism due to unpredictable corneal wound healing Induces myopic shift due to decreased corneal thickness Reduces corneal astigmatism by minimizing incision-induced changes Shifts the astigmatic axis to a more oblique orientation None 174. Cataract Surgery Why are some intraocular lenses designed to filter blue light? To improve dark adaptation by blocking peripheral scatter To reduce phototoxic damage to the retina and improve contrast sensitivity To decrease pupil constriction and increase retinal illumination To enhance near vision by selectively focusing shorter wavelengths None 175. Cataract Surgery How do Extended Depth of Focus (EDOF) intraocular lenses achieve a continuous range of vision? Increased asphericity to induce controlled spherical aberrations Use of chromatic aberration correction to extend focal points Elimination of multiple focal points to create a single elongated focus Pinhole optics to minimize out-of-focus blur None 176. Cataract Surgery Why might a surgeon implant a secondary (piggyback) IOL in a pseudophakic patient? To improve depth perception in monovision patients To reduce spherical aberrations caused by the first IOL To compensate for posterior capsule opacification To correct significant residual refractive error None 177. Cataract Surgery Which optical phenomenon is most likely to affect visual quality in patients with small pupils after multifocal IOL implantation? Increased chromatic aberration due to pupil-dependent refraction Reduced effect of multifocal optics leading to poor near vision Widening of peripheral field with loss of central clarity Increased depth of focus but reduced contrast sensitivity None 178. Cataract Surgery Why are negative-power IOLs sometimes required for extremely high myopia in cataract surgery? Negative lenses enhance retinal image magnification in myopic patients A posteriorly placed IOL requires negative power for proper light convergence The natural crystalline lens has strong positive power, and its removal necessitates a negative correction Negative lenses compensate for elongated axial length by neutralizing corneal power None 179. Cataract Surgery What optical aberration is most commonly induced when an IOL is significantly decentered postoperatively? Chromatic aberration Coma Barrel distortion Spherical aberration None 180. Cataract Surgery How does reverse optic capture influence refractive outcomes in IOL implantation? Pushes the IOL posteriorly to induce a hyperopic shift Increases posterior capsule opacification by trapping lens fibers Minimizes glare and halos by reducing light scatter at the IOL edge Reduces higher-order aberrations by stabilizing the IOL None 181. Cataract Surgery What optical principle contributes to positive dysphotopsia in some IOL patients? Excessive chromatic dispersion from multifocal optics Light scattering due to incomplete posterior capsule opacification Internal reflection of light at the IOL edge Pupil-dependent refraction misalignment None 182. Refractive Surgery Which of the following is not a complication of refractive eye surgery? Glare PCO DLK Dry eyes None 183. Refractive Surgery How long should soft contact lenses be withheld for before undergoing laser eye surgery? 7-14 days 28-35 days 14-21 days 21-28 days None 184. Refractive Surgery A corneal flap is created, the storm is then ablated, and the flap is replaced. what is this a description of? YAG laser capsulotomy LASEK LASIK PRK None 185. Refractive Surgery Which of the following is not an intervention for myopic correction? Negative diopter lens Central corneal ablation with LASIK Peripheral corneal ablation with LASIK Central corneal ablation with LASEK None 186. Refractive Surgery Which of the following is a key difference between PRK and LASIK? PRK does not require a corneal flap LASIK has a slower visual recovery than PRK PRK removes less corneal tissue than LASIK LASIK has a higher risk of corneal haze None 187. Refractive Surgery Which of the following is a contraindication for LASIK surgery? History of dry eyes Keratoconus Presbyopia A) Mild myopia (-2.00D) None 188. Refractive Surgery Why might a phakic IOL (ICL) be preferred over LASIK in some patients? LASIK is the only option for high myopia LASIK is more effective Phakic IOLs preserve the cornea Phakic IOLs are only used in presbyopia None 189. Refractive Surgery What is the primary advantage of SMILE (Small Incision Lenticule Extraction) over LASIK? No need for a femtosecond laser Less risk of dry eye Faster recovery Better correction of hyperopia None 190. Refractive Surgery Which instrument is the most accurate for measuring anterior chamber depth? Slit lamp with Van Herick technique Direct ophthalmoscope Pentacam (Scheimpflug imaging) Indirect ophthalmoscope None 191. Refractive Surgery Why are IOL power calculations more challenging in post-LASIK patients? The effective lens position is unpredictable due to changes in corneal biomechanics The axial length is affected by previous refractive surgery Corneal power is inaccurately estimated due to altered curvature The residual epithelial thickness alters the refractive index of the cornea None 192. Retinal Surgery Which optical phenomenon contributes to improved visualization of the retina during surgery under a microscope? Enhancement of retinal contrast via polarized light filtering Total internal reflection at the vitreous-retinal interface Reduction of spherical aberration using coaxial illumination Light scattering due to small pupil size None 193. Retinal Surgery Silicone oil in aphakic eye leads to? No change Myopic shift Hyperopic shift Blindess None 194. Retinal Surgery Why are wide-angle viewing systems preferred in modern retinal surgery? They magnify the central retina, allowing for more detailed surgical precision They increase image brightness by eliminating reflections from the corneal surface They provide a panoramic view of the peripheral retina without requiring frequent lens adjustments They reduce chromatic aberration and enhance color contrast in retinal structures None 195. Retinal Surgery Which optical property makes perfluorocarbon liquids (PFCL) useful in vitreoretinal surgery? High viscosity, preventing intraoperative turbulence Low refractive index, improving light transmission through the vitreous High specific gravity allowing mechanical flattening of the retina Selective absorption of short-wavelength light, reducing phototoxicity None 196. Retinal Surgery Which refractive change is commonly observed following pars plana vitrectomy with gas tamponade? Myopic shift Astigmatic shift Hyperopic shift No significant refractive change None 197. Retinal Surgery Which optical aberration is most commonly encountered when performing wide-field retinal imaging? Coma from off-axis light sources Spherical aberration from excessive lens curvature Distortion due to peripheral magnification differences Chromatic aberration from lens dispersion None 198. Retinal Surgery What optical principle makes endoillumination essential for vitreoretinal surgery? High refractive index of fiber optics ensures focused light delivery Total internal reflection of fiber-optic light enhances contrast Polarization reduces glare and enhances macular detail Scattering within the vitreous helps illuminate deep retinal layers None 199. Prescriptions Which bifocal segment design provides the widest near reading area? Round-segment bifocal Executive bifocal Flat-top bifocal Progressive lens None 200. Prescriptions Which of the following is an advantage of soft contact lenses over RGP lenses? Higher oxygen permeability More effective in correcting keratoconus Lower risk of corneal infections Better initial comfort None 201. Prescriptions An adult has diplopia and a left hypertrophic of 6Δ. which combination of prisms in his glasses will most likely align the two images for him? 6Δ base down (OD), nothing (OS) 4Δ base down (OD), 2Δ base down (OS) 3Δ base up(OD), 3Δ base down (OS) 3Δ base down (OD), 3Δ base up (OS) None 202. Prescriptions Which test is commonly used to measure the amplitude of accommodation? Bagolini striated lenses Push-up test Worth 4-dot test Maddox rod test None 203. Prescriptions What type of image distortion is most common with high-plus (hyperopic) lenses? Coma Pincushion distortion Barrel distortion Chromatic aberration None 204. Prescriptions What strength of lens is needed so that a patient with 20/160 visual acuity can read newsprint without accommodation? +12.50 D +8.00 D +5.00 D +10.00 D None 205. Prescriptions Which aberration is reduced by using aspheric lenses? Coma Chromatic aberration Distortion Spherical aberration None 206. Prescriptions A Maddox rod is place in front of a patient's right eye with its axis vertical. She is asked to look at a white spot and sees a horizontal red line with the light above it. What does that indicate? Exophoria Right hypophoria Right hyperphoria Esophoria None 207. Prescriptions You use the duochrome test to refine the refraction of a patient. The patient says the red letter are much clearer than the green. The patient is: Astigmatic Anisometropic Overminused Overplussed None 208. Prescriptions Which optical issue do progressive lenses correct that bifocals do not? High astigmatism Near vision Distance vision Intermediate vision None 209. Prescriptions What is the primary purpose of the Jackson Cross Cylinder (JCC) test? To determine near addition power To assess accommodation ability To measure spherical refractive error To refine the axis and power of astigmatism None 210. Prescriptions What type of patient benefits the most from myodisc lenses? Astigmatism Presbyopia High myopia High hyperopia None 211. Prescriptions What is the primary purpose of an anti-reflective coating on eyeglass lenses? To prevent all light from entering the eye To increase light reflection for better contrast To reduce glare and ghost images To create a mirror effect on the lens surface None 212. Prescriptions The base curve of a contact lens is primarily chosen based on which measurement? Central keratometry readings Pupil size Anterior chamber depth Lens diameter None 213. Prescriptions What is a key advantage of Fresnel prisms in ophthalmic use? They provide higher magnification. They do not require refraction correction. They reduce chromatic aberration. They are lightweight and flexible. None 214. Prescriptions Which function of the tear film is most critical for successful contact lens wear? Removing debris from the eye Maintaining corneal hydration Creating a smooth optical surface Providing nutrients to the cornea None 215. Prescriptions What is unique about gradient index (GRIN) lenses compared to standard lenses? They work only for concave lenses. They have a uniform refractive index throughout the material. They can only be used in microscopes. They have a continuously varying refractive index. None 216. Prescriptions In clinical practice, a Maddox rod is used to assess which of the following? Visual acuity Intraocular pressure Color vision Ocular alignment None 217. Prescriptions How does increasing the base curve radius affect a contact lens fit? It loosens the lens fit. It has no effect on fit. It increases the lens power. It tightens the lens fit. None 218. Prescriptions What is the primary effect of high-minus spectacle lenses on retinal image size? It induces a prismatic shift. It has no effect on image size. It reduces image size. It increases magnification. None 219. Prescriptions Which type of spherical lens is used to correct myopia? Convex (converging) lens Plano-convex lens Concave (diverging) lens Cylindrical lens None 220. Prescriptions Which optical phenomenon may cause double vision when a prism is incorrectly placed in spectacles? Ghosting Image displacement Monocular diplopia Chromatic aberration None 221. Prescriptions How does a pinhole improve vision in a hyperopic patient? It magnifies the image. It increases depth of focus by reducing peripheral blur. It increases the corneal curvature. It increases accommodation. None 222. Prescriptions What is the primary purpose of a retinoscope in clinical practice? To visualize the anterior chamber To assess intraocular pressure To measure refractive error objectively To examine the retina None 223. Prescriptions Which type of contact lens is most commonly used to correct aphakia? Hybrid lens with aspheric optics Scleral lens High-plus silicone hydrogel soft lens Rigid gas-permeable (RGP) corneal lens None 224. Prescriptions Which of the following is a correct transcription of a 0.50 Jackson's Cross cylinder? +0.25 DS/ -0.25 DC +0.25 DS/ -0.50 DC +0.50 DS/ -0.25 DC +0.50 DS/ -0.50 DC None 225. Prescriptions Regarding the Jackson's cross cylinder? The cylinder in the cross cylinder has twice the power of the sphere The cross cylinder's handle is held in line with the axis of the trial cylinder The handle is traditionally in line with the axis of the negative cylinder It is equivalent to two superimposed cylindrical lenses with axes at 45 degrees to each other None 226. Prescriptions Which is least likely in spectacle correction for aphakia? Ring scotoma Pin fusion distortion Image magnification Barrel distortion None 227. Prescriptions Which of the following regarding contact lenses is used in patients with dry eyes? Monthly lenses Silicone hydrogel Soft lenses Rigid lenses None 228. Prescriptions A patient is fitted with a rigid gas permeable contact lens. The average K reading is 7.67mm, and the base curve of the lens in 7.5 mm. What is the shape of the resultant tear lens? Plano No tear lens will be formed Convex Concave None 229. Prescriptions In a myopic patient, which of the following is increased with contact lens wear compared to glasses? Image distortion Image magnification Optical aberrations Aniseikonia None 230. Prescriptions Which of the following statement is correct regarding the segment choice when prescribing bifocals for a patient with hyperopia? The use of a round-top segment reduces the prismatic displacement effect and increases image jump The practitioner should leave the choice of the segment type to the optician, A flat-top segment is preferred because of its thin upper edge which causes less prismatic effect A round-top segment is preferred because it lessens image jump None 231. Prescriptions A patient with a red Maddox rod with the cylinders orientated horizontally placed over her left eye. What does she see when she views a distant white fixation light? Red light, horizontal red line Red light, vertical red line White light, vertical red line White light, horizontal red line None 232. Astigmatism Which of the following is an advantage of rigid gas permeable (RGP) contact lenses over soft lenses? Reduced risk of corneal hypoxia Greater initial comfort Higher oxygen permeability Does not require lens care None 233. Astigmatism Which type of lens is used to correct astigmatism? Plano-convex lens Prism lens Cylindrical lens Spherical lens None 234. Astigmatism In against-the-rule (ATR) astigmatism, the steepest meridian is located at approximately: 180° 135° 45° 90° None 235. Astigmatism In simple myopic astigmatism, how does light focus? One focal point is on the retina, and the other is behind the retina. Both focal points are in front of the retina. Both focal points are behind the retina. One focal point is on the retina, and the other is in front of the retina. None 236. Astigmatism What type of astigmatism is more commonly seen in older adults? Irregular astigmatism Oblique astigmatism Against-the-rule astigmatism With-the-rule astigmatism None 237. Astigmatism In a cylindrical lens, where does the full power of the lens act? Perpendicular to the axis Along the axis At 45° to the axis Evenly across the entire lens None 238. Astigmatism In a patient with regular astigmatism, how are the principal meridians positioned? Perpendicular to each other Randomly aligned Parallel to each other At 30-degree intervals None 239. Astigmatism Where does a cylindrical lens exert its refractive power? Along the axis of the lens Perpendicular to the axis of the lens At the center of the lens Equally across the entire lens None 240. Astigmatism A patient’s vision improves with a stenopaic slit placed at 90°. What type of refractive error does this suggest? Against-the-rule astigmatism Simple hyperopia With-the-rule astigmatism Simple myopia None 241. Astigmatism Which of the following is used to manage keratoconus? LASEK Rigid contact Lenses Toric lenses LASIK None 242. Astigmatism In simple hypermetropic astigmatism? The focal lines are straddling the retina One focal line is on the retina whilst the other is behind it Both focal lines are in front of the retina Both focal lines are behind the retina None 243. Astigmatism Which of the following prescriptions is an example of 'with the rule' astigmatism? -5.25 DS/ +2.50 DC axis 180 +3.50 DS/ -0.75 DC axis 90 -1.50 DS/ -1.00 DC axis 45 +3.00 DS/ +2.25 DC axis 85 None 244. Astigmatism Keratoconus most likely causes? Axial myopia Axial hypermetropia Refractive myopia Refractive hypermetropia None 245. Astigmatism If rays of light from all meridians come into focus behind the retina, this is called? Simple hypermetropic astigmatism Simple myopic astigmatism Compound hypermetropic astigmatism Compound myopic astigmatism None 246. Low Vision Aids Which low vision aid can help a patient with Age Related Macular Degeneration watch TV? Magnifying glass Galilean telescope Hubble telescope loop magnifiers None 247. Low Vision Aids What is the primary purpose of low vision aids in the management of patients with visual impairment? To magnify images for clearer vision To treat underlying eye diseases To restore normal vision To eliminate the need for corrective lenses None 248. Low Vision Aids Which of the following low vision aids is best suited for improving distance vision in individuals with low vision? Magnification spectacles Bifocal lenses Reading glasses Telescopic lenses None 249. Low Vision Aids Which of the following low vision aids is most commonly used for close-up tasks such as reading? Telescopic lenses Fresnel prisms High-powered magnifying glasses Visual field expanders None 250. Low Vision Aids Which of the following statements about the Galilean telescope is least likely? It has an extremely narrow field of view The image is typically dimmer than seen with the unaided eye It is composed of two convex lenses The objective and eye piece lenses are separated by the difference between their focal lengths None 251. Low Vision Aids What role do prisms play in binoculars? They increase the brightness of the image. They invert and erect the image. They reduce chromatic aberration. They allow light to be focused at a single point. None 252. Low Vision Aids Which of the following best describes the image produced by a Galilean telescope? Virtual, inverted, magnified, at the sum of the focal lengths of the object and eyepiece lens Virtual, erect, magnified, at the sum of the focal lengths of the objective and eyepiece lens Virtual, erect, magnified at infinity Virtual, inverted, magnified, at infinity None 253. Low Vision Aids Which optical application commonly uses a plano-convex lens? Magnifying glass Myopia correction Optical fiber focusing Camera telephoto lens None 254. Clinical Which of the following is not associated with myopia? RRD Uveal effusion syndrome ROP Congenital glaucoma None 255. Clinical Which of the following is used to distinguish between open and closed angle glaucoma? Fundoscopy Perimetry Gonioscopy Tonometry None 256. Clinical What investigation is used to measure corneal curvature? Pachymetry Tonometry Keratometry Perimetry None 257. Clinical A patient with presbyopia says he can now see without his reading glasses, Which cataract does the patient have? Posterior subcapsular Anterior subcapsular Nuclear sclerotic Cortical None 258. Clinical Which of the following structures is affected leading to presbyopia? Zonules Iris Lens Cornea None 259. Clinical Which of the following factors increases the risk of infection in a patient using extended wear contact lenses? Exposure to smoke Intact corneal epithelium Switching to daily -wear contacts Normal eyelid function None 260. Clinical Regarding the prevalence of myopia (of at least -0.5 dioptres): It is high in white Europeans compared to other ethnicities Myopis tends to decrease with nuclear sclerosis of the lens It is lower in adults than in young children Time spent outdoors as a child is a protective factor agains myopia None 261. Clinical A child has a cycloplegia refraction 0D +6.00D, OS +2.00. What is the best way to manage the anisometropia? Occlusion therapy Partial correction Full correction Paleoptic therapy None 262. Clinical Which lens can be used to examine the anterior chamber angle? 90D lens Three mirror lens Wide field lens Hruby lens None 263. Clinical Which of the following indirect ophthalmoscopy lenses gives the greater magnification? 20 D 30 D 28 D 15 D None 264. Clinical How does corneal edema primarily affect vision? Enhances contrast sensitivity Causes hyperopia Increases light scatter Induces myopia None 265. Clinical Which of the following is a common optical correction for presbyopia? Plano convex lenses Progressive addition lenses (PALs) Single-vision myopic glasses Cylindrical lenses None 266. Clinical What is the primary cause of presbyopia? Corneal steepening Weakening of the extraocular muscles Loss of lens elasticity Increase in axial length None 267. Clinical Which factor is least likely to influence the onset of presbyopia? Age Gender Geographic location Refractive error None 268. Spherical Lenses How is the image formed by a convex lens of an object located inside the first focal point best described? Erect, real, inside age second focal point, diminished Inverted, virtual, at infinity, diminished Inverted, real, outside the second focal point, magnified Erect, virtual, further from lens than object, magnified None 269. Spherical Lenses What role does a concave lens play in a Keplerian telescope? It increases the field of view while maintaining image size It enhances color contrast by removing chromatic aberration It corrects the inverted image formed by the convex objective lens It magnifies the image without altering the focal length None 270. Spherical Lenses For a convex lens, placing an object outside the first principle focus results in an image that is Magnified, inverted, virtual Erect, real Enlarged, erect, virtual Inverted, real None 271. Spherical Lenses A higher refractive index lens has which of the following advantages? Increased spherical aberrations Reduced lens thickness Increased lens thickness Increased chromatic aberration None 272. Spherical Lenses The image formed by a thin concave lens is? Real, inverted, magnified, outside the second focal point Real erect, magnified, further from the lens than the object Virtual, inverted, diminished at infinity Virtual, erect, diminished, inside the second focal point None 273. Spherical Lenses Tilting a spherical lens can induce which type of optical effect? Induced prism Reduced power No effect Elimination of aberrations None 274. Spherical Lenses What happens when the curvature of a spherical lens increases? The refractive index of the lens material changes The focal length decreases, making the lens more powerful The lens starts to behave like a prism instead of a spherical lens The focal length increases, reducing the lens’s optical power None 275. Spherical Lenses Which factor increases the optical power of a spherical lens, assuming the shape remains the same? Using a material with a higher refractive index Decreasing the thickness of the lens Reducing the curvature of the lens surfaces Increasing the focal length of the lens None 276. Spherical Lenses What type of image is always produced by a concave (diverging) spherical lens? Virtual, inverted, and same size as the object Real, upright, and larger than the object Virtual, upright, and smaller than the object Real, inverted, and magnified None 277. Spherical Lenses Which factor increases the optical power of a spherical lens, assuming the shape remains the same? Increasing the focal length of the lens Decreasing the thickness of the lens Reducing the curvature of the lens surfaces Using a material with a higher refractive index None 278. Spherical Lenses Which statement is true regarding the difference between a biconcave and a plano-concave lens? A plano-concave lens is used to converge light rays A plano-concave lens has equal power on both sides A biconcave lens forms only real images A biconcave lens has two concave surfaces and more negative power None 279. Spherical Lenses What happens to the focal length of a convex lens when it is submerged in water? It depends only on the lens curvature, not the surrounding medium It remains the same because focal length is a material property It increases because the refractive index contrast between the lens and water is reduced It decreases because water enhances light bending None 280. Jokes 😉 Why do people randomly test themselves for color blindness online? Because it’s a convenient way to procrastinate at work. Because they need to know whether they’d survive as a bomb defuser in an action movie. Because they want to prove their friends wrong in an argument about "blue or green?" Because they saw a meme that convinced them they’ve been colorblind their whole life. None 281. Jokes 😉 What’s the real reason optometrists get excited about astigmatism? Because they secretly enjoy watching patients struggle with JCC testing. Because saying “with-the-rule astigmatism” makes them feel fancy. Because prescribing cylindrical correction makes them feel like wizards. Because it’s a good excuse to show off their maths skills. None 282. Jokes 😉 What is the most common reaction after LASIK surgery? “Wow, I can see! Time to read the fine print on my medical bills.” “Can I get a refund if I still need glasses?” “My vision is so clear, I can now see all my life mistakes.” “So… I paid thousands of dollars and now I have dry eyes forever?” None 283. Properties of Light A beam of light passes from air into glass at an angle. What happens to its frequency? It becomes zero. It increases. It decreases. It remains the same. None 284. Properties of Light Which of the following is least likely to happen when constructing a correct ray diagram? Rays that do not intersect will eventually converge if extended. If the rays appear to diverge, a virtual image is formed. At least two rays are required to locate an image. The image forms where the reflected or refracted rays intersect. None 285. Properties of Light Destructive interference is most likely in: Corneal epithelium Refraction Corneal endothelium Antireflective lens coatings None 286. Properties of Light When light moves from air to water and travels towards the normal at the interface, which of the following is more likely to happen? The light will not bend at all. The light will undergo total internal reflection. The light will bend away from the normal The light will bend towards the normal. None 287. Properties of Light Which statement about the speed of light is correct? Light travels fastest in water. Light slows down when entering a denser medium. Light travels at the same speed in all mediums. Light speeds up when entering a denser medium. None 288. Properties of Light Which of the following terms best describes a substance which only allows the transmission of light in an incident plane aligned with its structure, by absorbing other light waves? Mirrored Scattering Dichroic birefringent None 289. Properties of Light Which of the following is most likely the correct rule for drawing a principal ray in a concave mirror ray diagram? A ray incident at the mirror surface always travels straight without reflection. A ray passing through the centre of curvature (C) reflects at a random angle. A ray passing through the focal point (F) reflects parallel to the principal axis. A ray parallel to the principal axis reflects through the center of curvature (C). None 290. Properties of Light Which change is most likely when a ray of light passes into a denser medium? Frequency and plane Velocity and frequency Velocity only Velocity and plane None 291. Properties of Light Which definition most likely describes radiant flux? The intensity if light emitted from a source The amount of light falling in a surface The amount of light emitted from a source The amount of light reflected from a surface None 292. Properties of Light The image of an object formed by reflection at a plane surface is least likely to be? Erect Laterally inverted Diminished Virtual None 293. Properties of Light How is surface illumination related to the distance from the light source? Directly proportional Directly proportional to the square root Inversely proportional Inversely proportional the square root None 294. Properties of Light Regarding optical radiation, which of the following is least likely? Light emitted through fluorescence typically has a longer wavelength than the excitation light that trigger it The wavelength of light decreases as it enters a transparent material from a vacuum Shorter wavelengths undergo increased scatter The energy of a photon is directly proportional to its wavelength None 295. Properties of Light What causes the appearance of a secondary rainbow? Diffraction of light waves A different type of water droplet composition A change in the sun’s intensity Multiple internal reflections inside raindrops None 296. Properties of Light Wavelength is best defined as? The maximum displacement of an imaginary particle on the wave from the baseline Any portion of the cycle The distance between two symmetrical parts of the wave motion One complete oscillation None 297. Properties of Light What type of reflection occurs on a rough surface? Diffuse reflection Polarized reflection Specular reflection Total internal reflection None 298. Properties of Light What does polarized light consist of? Light waves oscillating in multiple planes Light waves oscillating in a single plane Light waves with reduced intensity Light waves with equal wavelengths None 299. Properties of Light Total internal reflection occurs is most likely if the incident ray strikes the interface of media at? The critical angle An angle greater than the critical angle An angle less than the critical angle 90 degrees None 300. Properties of Light The most likely unit of illuminance is? Watts per steradian Cadelas (lumen per steradian) Lux (human per square metre) Lumen None 301. Properties of Light Which catastrophic image is most likely to form an inverted image? Add description here! Posterior lens surface Anterior corneal surface Anterior lens surface Posterior corneal surface None 302. Properties of Light Which type of light wave carries the most energy? Infrared light Ultraviolet light Red light Blue light None 303. Properties of Light Which of the following statements about convave lenses is TRUE? They cause light to diverge They are used to correct myopia They always produce virtual images They converge parallel light rays to a focal point None 304. Properties of Light Which of the following correctly describes light? It is a longitudinal wave. It requires a medium to travel. It can exhibit both wave and particle properties. It travels at the same speed in all materials. None 305. Properties of Light Which of the following factors affects the scattering of light in the eye? Wavelength of light Intraocular pressure Corneal thickness Lens elasticity None 306. Properties of Light What is the main law governing the reflection of light? Law of Equal Angles Snell’s Law Brewster’s Law Fermat’s Principle None 307. Properties of Light What happens to light as it moves from a less dense medium (air) to a denser medium (cornea)? It remains unaltered It bends away from the normal It slows down and bends toward the normal It speeds up None 308. Properties of Light Which of the following pairs is matched correctly? Prism diopter-meters per centimetre Dioptre-meter Refractive index-meters per second Wavelength-nanometers None 309. Properties of Light Which of the following statements about convex lenses is TRUE? They cause light to diverge They are used to correct myopia They converge parallel light rays to a focal point They always produce virtual images None 310. Properties of Light Which optical principle explains the formation of mirages? Dispersion Reflection Refraction Diffraction None 311. Properties of Light Which color of visible light has the shortest wavelength? Red Yellow Green Blue None 312. Properties of Light When the angle of incidence is greater than the critical angle? The angle of incidence cannot be greater than the critical angle Total Internal reflection occurs Total external refraction occurs Reflection mostly occurs with some refraction None Please fill in the comment box below. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time's up
