Continue learning Elementary & Physiological Optics mcq – Section 1: Basic Optics (Batch 2: Q41–80) with detailed MCQs on optical systems, eye models, mirrors, prisms, lenses, and aberrations. Covers Listing’s and Gullstrand’s schematic eyes, retinoscopy, prism bases, keratometry, astigmatism types, and optical aberrations — essential for NEET PG, AIIMS, INI-CET, and Optometry mcq for exams.
Optical Systems & Eye Models
41. The reduced eye model was described by:
A. Helmholtz
B. Gullstrand
C. Listing
D. Donders
View Answer
C. Listing ✅ Exp: Listing’s reduced eye simplifies optics with single refracting surface.
42. Gullstrand’s schematic eye has how many refracting surfaces?
A. 2
B. 4
C. 6
D. 8
View Answer
C. 6 ✅ Exp: More detailed than reduced eye; 6 surfaces used.
43. Total refractive power of cornea is approximately:
A. 20 D
B. 43 D
C. 50 D
D. 60 D
View Answer
B. 43 D ✅ Exp: Cornea contributes ~2/3rd of eye’s power.
44. Total refractive power of crystalline lens is about:
A. 10 D
B. 17 D
C. 25 D
D. 30 D
View Answer
B. 17 D ✅ Exp: Lens adds ~17 D, variable with accommodation.
45. Far point of an emmetropic eye lies at:
A. 1 m
B. Infinity
C. 25 cm
D. Retina
View Answer
B. Infinity ✅ Exp: Parallel rays from infinity focus on retina.
46. Near point of accommodation in young adults is:
A. 25 cm
B. 1 m
C. Infinity
D. 6 m
View Answer
A. 25 cm ✅ Exp: Standard near point ≈ 25 cm.
47. Nodal point of reduced eye lies about:
A. 5 mm in front of retina
B. 7 mm in front of retina
C. At corneal apex
D. At lens equator
View Answer
B. 7 mm in front of retina ✅ Exp: Nodal point ~7 mm from retina.
48. Axial length of normal adult eye:
A. 20 mm
B. 22–24 mm
C. 26–28 mm
D. 30 mm
View Answer
B. 22–24 mm ✅ Exp: Average ~23 mm.
49. Each mm increase in axial length produces approximately:
A. 1 D myopia
B. 3 D myopia
C. 5 D myopia
D. 0.5 D myopia
View Answer
B. 3 D myopia ✅ Exp: 1 mm = ~3 D refractive error.
50. Accommodation is absent in:
A. Emmetropia
B. Presbyopia
C. Myopia
D. Astigmatism
View Answer
B. Presbyopia ✅ Exp: Presbyopia is loss of accommodation with age.
Reflection & Mirrors
51. The principle of retinoscopy is based on:
A. Reflection of light from cornea only
B. Reflection of light from retina
C. Refraction through lens
D. Total internal reflection
View Answer
B. Reflection of light from retina ✅ Exp: Uses retinal reflex to measure refractive error.
52. The ophthalmoscope works on the principle of:
A. Refraction
B. Reflection
C. Diffraction
D. Total internal reflection
View Answer
B. Reflection ✅ Exp: Light reflects off retina into examiner’s eye.
53. Concave mirrors produce:
A. Virtual erect image
B. Real inverted image (when object beyond focus)
C. Always magnified virtual image
D. No image
View Answer
B. Real inverted image (when object beyond focus) ✅ Exp: Ophthalmoscopes may use concave mirrors.
54. Plane mirror in retinoscope is used for:
A. Hypermetropia
B. Emmetropia
C. Myopia
D. All types of refraction
View Answer
D. All types of refraction ✅ Exp: Both plane and concave mirrors are useful depending on error.
55. The cat’s eye reflex (Brückner’s test) is based on:
A. Retinal reflection
B. Corneal curvature
C. Accommodation
D. Lens opacities
View Answer
A. Retinal reflection ✅ Exp: Used to detect squint and anisometropia in children.
56. Prism base-out moves image:
A. Outward
B. Inward
C. Upward
D. Downward
View Answer
B. Inward ✅ Exp: Base-out displaces image toward apex, forcing convergence.
57. Prism base-in used for:
A. Esotropia
B. Exotropia
C. Hypermetropia
D. Myopia
View Answer
B. Exotropia ✅ Exp: Base-in stimulates divergence → exotropia correction.
58. Prisms are measured in:
A. Degrees
B. Prism diopters
C. Minutes of arc
D. Millimeters
View Answer
B. Prism diopters ✅ Exp: Ophthalmic use = prism diopters.
59. In retinoscopy, “with movement” reflex indicates:
A. Myopia >1D
B. Hypermetropia
C. Emmetropia
D. Low myopia (<1D)
View Answer
B. Hypermetropia ✅ C. Emmetropia ✅ D. Low myopia (<1D) ✅B. Hypermetropia ✅ Exp: With-movement occurs in hypermetropia, emmetropia, or low myopia.
60. In retinoscopy, “against movement” reflex indicates:
A. Hypermetropia
B. Myopia >1D
C. Emmetropia
D. Astigmatism only
View Answer
B. Myopia >1D ✅ Exp: Against movement = higher myopia.
Lens Optics
61. +10 D lens focal length:
A. 1 cm
B. 10 cm
C. 20 cm
D. 25 cm
View Answer
B. 10 cm ✅ Exp: f = 1/10 = 0.1 m = 10 cm.
62. A –2 D lens has focal length of:
A. –50 cm
B. –20 cm
C. –100 cm
D. –10 cm
View Answer
A. –50 cm ✅ Exp: Negative sign indicates diverging.
63. Lens thickness increases in:
A. Accommodation
B. Presbyopia
C. Myopia
D. Aphakia
View Answer
A. Accommodation ✅ Exp: Ciliary contraction → zonule relaxation → thicker lens.
64. In aphakia, the total refractive power of eye reduces to:
A. 30 D
B. 43 D
C. 60 D
D. 80 D
View Answer
B. 43 D ✅ Exp: Only corneal power remains (~43 D).
65. Glass lenses are replaced in practice by:
A. Quartz
B. Plastic (CR-39, polycarbonate)
C. Acrylic
D. Sapphire
View Answer
B. Plastic (CR-39, polycarbonate) ✅ Exp: Lighter, safer, more durable.
Refractive Principles
66. Power of cornea depends on:
A. Anterior surface curvature
B. Posterior surface curvature
C. Both surfaces
D. Lens thickness
View Answer
A. Anterior surface curvature ✅ Exp: Major contribution from anterior corneal curvature.
67. The cornea-air interface is powerful because:
A. Big difference in refractive index
B. Thin structure
C. Uniform thickness
D. Presence of aqueous
View Answer
A. Big difference in refractive index ✅ Exp: n (air) = 1.0 vs cornea = 1.376.
68. Lenticular astigmatism arises from:
A. Lens curvature defects
B. Corneal irregularities
C. Tear film
D. Retina
View Answer
A. Lens curvature defects ✅ Exp: Caused by uneven lens surfaces.
69. A myope of –2 D without glasses sees clearly at:
A. Infinity
B. 25 cm
C. 50 cm
D. 1 m
View Answer
C. 50 cm ✅ Exp: Far point = 1/2 D = 0.5 m = 50 cm.
70. A hypermetrope of +2 D has far point at:
A. 25 cm behind retina
B. 50 cm behind retina
C. Infinity
D. 25 cm in front
View Answer
B. 50 cm behind retina ✅ Exp: Hypermetropic eye focuses behind retina.
71. Keratometry measures:
A. Corneal curvature
B. Axial length
C. Refractive index
D. Lens power
View Answer
A. Corneal curvature ✅ Exp: Used to assess corneal power, astigmatism.
72. Normal corneal curvature power is approximately:
A. 38 D
B. 43 D
C. 48 D
D. 55 D
View Answer
B. 43 D ✅ Exp: Normal ~43 D (range 41–45 D).
73. Spherical aberration occurs because:
A. Peripheral rays refract more than central
B. Different refractive indices
C. Chromatic dispersion
D. Accommodation
View Answer
A. Peripheral rays refract more than central ✅ Exp: Causes blurring of image.
74. Chromatic aberration occurs because:
A. Different wavelengths refract differently
B. Corneal curvature
C. Lens opacities
D. Tear film changes
View Answer
A. Different wavelengths refract differently ✅ Exp: Blue refracts more than red.
75. Astigmatism occurs due to:
A. Unequal refraction in different meridians
B. Increased axial length
C. Decreased axial length
D. Lens opacities
View Answer
A. Unequal refraction in different meridians ✅ Exp: Unequal meridian curvature.
76. Against-the-rule astigmatism means:
A. Vertical meridian steeper
B. Horizontal meridian steeper
C. Oblique axis
D. Irregular curvature
View Answer
B. Horizontal meridian steeper ✅ Exp: Steepest meridian is horizontal.
77. With-the-rule astigmatism means:
A. Vertical meridian steeper
B. Horizontal meridian steeper
C. Axis at 45°
D. Lens irregularity
View Answer
A. Vertical meridian steeper ✅ Exp: Vertical steepness is common.
78. An oblique astigmatism has axes around:
A. 0° and 90°
B. 45° and 135°
C. 30° and 60°
D. Random meridians
View Answer
B. 45° and 135° ✅ Exp: Axes not vertical/horizontal.
79. Regular astigmatism is corrected by:
A. Cylindrical lenses
B. Prism
C. Contact lens only
D. Surgery only
View Answer
A. Cylindrical lenses ✅ Exp: Regular = fixed meridians, corrected by cylinders.
80. Irregular astigmatism is best corrected by:
A. Cylindrical glasses
B. Rigid contact lenses
C. Spherical glasses
D. Surgery only
View Answer
B. Rigid contact lenses ✅ Exp: Irregular curvature corrected with RGP lenses.
✅ That’s 80 MCQs total from Section 1 (Basic Optics: Light, Reflection, Refraction, Prisms, Lenses).
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