Elementary & Physiological Optics – Section 2: Spherical and Cylindrical spectacle lenses (Batch 2: Q41–80) – Comprehensive MCQs with answers and short explanations on astigmatism types, spectacle lens effects, Prentice’s rule, lens materials, contact and toric lenses, aniseikonia, and anisometropia. Perfect for NEET PG, NEXT, AIIMS, INI-CET, and Optometry mcq for exam preparation.
Astigmatism Types & Corrections
41. Simple myopic astigmatism means:
A. Both meridians myopic
B. One emmetropic, one myopic
C. Both hypermetropic
D. Mixed error
View Answer
B. One emmetropic, one myopic ✅ Exp: One meridian focuses on retina, other in front.
42. Simple hypermetropic astigmatism means:
A. One emmetropic, one hypermetropic
B. Both meridians hypermetropic
C. Mixed correction
D. Presbyopic correction
View Answer
A. One emmetropic, one hypermetropic ✅ Exp: One meridian normal, other behind retina.
43. Compound myopic astigmatism means:
A. Both meridians myopic
B. Both hypermetropic
C. One emmetropic
D. Mixed error
View Answer
A. Both meridians myopic ✅ Exp: Both in front of retina.
44. Compound hypermetropic astigmatism means:
A. Both meridians hypermetropic
B. One hyper, one myopic
C. One emmetropic
D. Mixed correction
View Answer
A. Both meridians hypermetropic ✅ Exp: Both behind retina.
45. Mixed astigmatism means:
A. One meridian myopic, other hypermetropic
B. Both emmetropic
C. Both hypermetropic
D. Both myopic
View Answer
A. One meridian myopic, other hypermetropic ✅ Exp: Opposite signs → mixed astigmatism.
46. Regular astigmatism differs from irregular because:
A. Principal meridians are at right angles
B. No fixed meridians
C. Cannot be corrected
D. Always pathological
View Answer
A. Principal meridians are at right angles ✅ Exp: Regular has fixed axes; irregular is distorted.
47. Irregular astigmatism is best corrected by:
A. Cylindrical lenses
B. Rigid gas-permeable lenses
C. Soft contact lenses
D. Spectacles
View Answer
B. Rigid gas-permeable lenses ✅ Exp: RGP lenses neutralize irregular surface.
48. Keratoconus usually causes:
A. Regular astigmatism
B. Irregular astigmatism
C. Hypermetropia
D. Presbyopia
View Answer
B. Irregular astigmatism ✅ Exp: Cone-shaped cornea = irregular refraction.
49. With-the-rule astigmatism is common in:
A. Young adults
B. Elderly
C. Infants only
D. Aphakia
View Answer
A. Young adults ✅ Exp: Vertical meridian steeper in youth.
50. Against-the-rule astigmatism is common in:
A. Children
B. Elderly
C. Myopes
D. Post-cataract
View Answer
B. Elderly ✅ Exp: Horizontal steepness increases with age.
Spectacle Lens Effects
51. Plus lenses cause:
A. Image minification
B. Image magnification
C. No change
D. Barrel distortion
View Answer
B. Image magnification ✅ Exp: Converging lenses enlarge image.
52. Minus lenses cause:
A. Image magnification
B. Image minification
C. Same size
D. Ring scotoma
View Answer
B. Image minification ✅ Exp: Diverging lenses reduce image size.
53. Ring scotoma (jack-in-the-box) is caused by:
A. Minus lenses
B. High plus lenses
C. Cylindrical lenses
D. Contact lenses
View Answer
B. High plus lenses ✅ Exp: Edge magnification of aphakic spectacles.
54. Spectacle magnification of +10 D lens is about:
A. 5%
B. 20%
C. 40%
D. 50%
View Answer
B. 20% ✅ Exp: Aphakic spectacles enlarge ~20%.
55. Minus spectacle lenses have thick edges, causing:
A. Barrel distortion
B. Pincushion distortion
C. Spherical aberration
D. Ring scotoma
View Answer
A. Barrel distortion ✅ Exp: Minus lenses cause barrel effect.
56. Decentration of + lens produces:
A. Base-in effect
B. Prism effect toward decentration
C. No effect
D. Random distortion
View Answer
B. Prism effect toward decentration ✅ Exp: According to Prentice’s rule.
57. Prentice’s rule formula:
A. P = c × F
B. P = 1/f
C. P = (n–1)/R
D. P = d/f
View Answer
A. P = c × F ✅ Exp: Prism diopters = decentration (cm) × lens power.
58. A +5 D lens decentered by 2 cm produces prism of:
A. 5 Δ
B. 10 Δ
C. 15 Δ
D. 2.5 Δ
View Answer
B. 10 Δ ✅ Exp: P = 2 × 5 = 10 prism diopters.
59. Prisms in spectacles are usually incorporated for:
A. Presbyopia
B. Strabismus correction
C. Myopia correction
D. Aphakia
View Answer
B. Strabismus correction ✅ Exp: Used to relieve diplopia or muscle imbalance.
60. Base-out prism is used for:
A. Exotropia correction
B. Esotropia correction
C. Myopia
D. Hypermetropia
View Answer
A. Exotropia correction ✅ Exp: Base-out forces convergence → exotropia help.
Clinical Applications & Tests
61. Jackson’s cross cylinder is used to:
A. Refine astigmatism correction
B. Detect presbyopia
C. Measure axial length
D. Assess IOP
View Answer
A. Refine astigmatism correction ✅ Exp: Used at phoropter for final cylinder axis/power.
62. Cross-cylinder test helps in:
A. Determining spherical correction
B. Determining cylinder axis and power
C. Measuring accommodation
D. Assessing corneal curvature
View Answer
B. Determining cylinder axis and power ✅ Exp: Essential step in refraction.
63. Stenopaic slit is used to diagnose:
A. Presbyopia
B. Astigmatism
C. Myopia
D. Hypermetropia
View Answer
B. Astigmatism ✅ Exp: Isolates one meridian for testing.
64. Retinoscopy identifies astigmatism by:
A. Neutralization
B. With/against movement in different meridians
C. Spherical lens trial
D. Using prisms
View Answer
B. With/against movement in different meridians ✅ Exp: Reflex differs in different axes.
65. Trial lens axis adjustment in astigmatism correction is usually:
A. 10° steps
B. 5° steps
C. 20° steps
D. 1° steps
View Answer
B. 5° steps ✅ Exp: Refined in 5° increments.
Spectacle Lens Materials
66. CR-39 is a:
A. Glass lens
B. Plastic lens
C. High-index glass
D. Polycarbonate
View Answer
B. Plastic lens ✅ Exp: Lightweight plastic material, widely used.
67. Polycarbonate lenses are preferred for:
A. Cosmetic use
B. Children & sports
C. Aphakia
D. Astigmatism
View Answer
B. Children & sports ✅ Exp: Impact resistant, thin, safe.
68. High-index plastic lenses advantage:
A. Heavier
B. Thinner & lighter
C. More chromatic aberration
D. Less safety
View Answer
B. Thinner & lighter ✅ Exp: High index reduces thickness.
69. Glass lenses are avoided in children because:
A. Costly
B. Brittle & unsafe
C. Heavy
D. Poor optics
View Answer
B. Brittle & unsafe ✅ Exp: Risk of injury → plastic preferred.
70. Scratch resistance is better in:
A. Plastic
B. Glass
C. Polycarbonate
D. CR-39
View Answer
B. Glass ✅ Exp: Glass lenses resist scratches better.
71. Contact lenses eliminate:
A. Ring scotoma in aphakia
B. Astigmatism
C. Myopia only
D. Presbyopia
View Answer
A. Ring scotoma in aphakia ✅ Exp: Reduce image distortion vs spectacles.
72. Toric contact lenses correct:
A. Presbyopia
B. Astigmatism
C. Hypermetropia only
D. Cataract
View Answer
B. Astigmatism ✅ Exp: Toric lenses have cylinder correction.
73. Bifocal spectacles are prescribed for:
A. Myopia
B. Hypermetropia
C. Presbyopia
D. Astigmatism
View Answer
C. Presbyopia ✅ Exp: Near and distance in one lens.
74. Progressive addition lenses (PAL) advantage:
A. Clear zones for near, intermediate, distance
B. Heavy weight
C. More distortions
D. No cosmetic value
View Answer
A. Clear zones for near, intermediate, distance ✅ Exp: Smooth power transition.
75. Lenticular lenses are used for:
A. High myopia correction
B. Low hyperopia
C. Presbyopia
D. Astigmatism
View Answer
A. High myopia correction ✅ Exp: Central optical zone reduces thickness.
76. Aniseikonia means:
A. Unequal image size in two eyes ✅
B. Unequal refractive error
C. Unequal corneal curvature
D. Diplopia
View Answer
A. Unequal image size in two eyes ✅ Exp: Caused by anisometropia, corrected by contact lenses.
77. Anisometropia means:
A. Different refractive errors in two eyes
B. Different axial length
C. Different image size
D. Corneal scar
View Answer
A. Different refractive errors in two eyes ✅ Exp: Difference >2 D can cause amblyopia.
78. Spectacle correction of anisometropia >3 D is avoided due to:
A. Diplopia
B. Aniseikonia
C. Blurring only
D. Headache
View Answer
B. Aniseikonia ✅ Exp: Large image size difference → poor fusion.
79. Contact lenses are better than spectacles in anisometropia because:
A. Cheaper
B. Reduce aniseikonia
C. Cosmetic only
D. More durable
View Answer
B. Reduce aniseikonia ✅ Exp: Contact lenses reduce magnification difference.
80. High myopia (>–10 D) spectacles cause:
A. Image magnification
B. Image minification
C. No change
D. Distortion-free vision
View Answer
B. Image minification ✅ Exp: Minus lenses reduce image size significantly.
