Elementary & Physiological Optics – Section 2: Spherical & Cylindrical Lenses (Batch 1: Q1–40) – Detailed MCQs with answers and short explanations covering spherical, cylindrical, and spherocylindrical lenses, lens aberrations, Prentice’s rule, toric lenses, and spectacle optics. Essential for NEET PG, NEXT, AIIMS, INI-CET, and Optometry mcq for exams.
Spherical Lenses – Basics
1. A spherical lens has:
A. Power only in one meridian
B. Equal power in all meridians
C. No refractive power
D. Different curvature in all directions
View Answer
B. Equal power in all meridians ✅ Exp: Spherical lens has uniform curvature → same power.
2. Convex lenses are also called:
A. Diverging lenses
B. Converging lenses
C. Cylindrical lenses
D. Plano lenses
View Answer
B. Converging lenses ✅ Exp: Convex → converging lens.
3. Concave lenses are:
A. Diverging lenses
B. Converging lenses
C. Neutral lenses
D. Astigmatic lenses
View Answer
A. Diverging lenses ✅ Exp: Concave lens diverges parallel rays.
4. Vergence of light at 50 cm distance is:
A. +2 D
B. +1 D
C. –2 D
D. 0.5 D
View Answer
C. –2 D ✅ Exp: Vergence L = 1/d (in meters). Object at 0.5 m → L = –2 D.
5. A convex lens of +4 D has focal length:
A. 25 cm
B. 50 cm
C. 100 cm
D. 10 cm
View Answer
A. 25 cm ✅ Exp: f = 1/4 = 0.25 m = 25 cm.
Types & Classification
6. Plano-convex lens has surfaces:
A. One plane, one convex
B. Both convex
C. One plane, one concave
D. Both concave
View Answer
A. One plane, one convex ✅ Exp: Common ophthalmic lens type.
7. Biconvex lens has:
A. Both convex surfaces
B. One concave, one convex
C. Both plane
D. One convex, one plano
View Answer
A. Both convex surfaces ✅ Exp: Symmetrical convex lens.
8. Meniscus lens is:
A. Convex-concave lens
B. Biconvex
C. Biconcave
D. Plano lens
View Answer
A. Convex-concave lens ✅ Exp: One convex, one concave surface.
9. High plus spectacle lenses are usually:
A. Plano-convex
B. Meniscus
C. Biconvex
D. Plano-concave
View Answer
B. Meniscus ✅ Exp: Meniscus design reduces aberrations.
10. Minus spectacle lenses are usually:
A. Plano-convex
B. Meniscus concave
C. Plano-concave
D. Cylindrical
View Answer
B. Meniscus concave ✅ Exp: Meniscus concave reduces distortions.
Cylindrical Lenses – Basics
11. Cylindrical lens has power in:
A. All meridians
B. Only one meridian
C. None
D. Opposite axes
View Answer
B. Only one meridian ✅ Exp: Cylindrical lens refracts only in one axis.
12. Axis of cylinder corresponds to:
A. Maximum power
B. Zero power
C. Average power
D. Base curve
View Answer
B. Zero power ✅ Exp: Axis is 90° to power meridian.
13. Cylindrical lenses correct:
A. Myopia
B. Hypermetropia
C. Astigmatism
D. Presbyopia
View Answer
C. Astigmatism ✅ Exp: Unequal refraction corrected by cylinders.
14. A +2 D cylinder at 90° means:
A. No power at 90°, +2 D at 180°
B. +2 D at 90°, none at 180°
C. Power in both meridians
D. No correction
View Answer
A. No power at 90°, +2 D at 180° ✅ Exp: Cylinder acts perpendicular to axis.
15. Cross cylinder is used for:
A. Astigmatism refinement
B. Presbyopia
C. Myopia only
D. Aphakia
View Answer
A. Astigmatism refinement ✅ Exp: Jackson’s cross cylinder in refraction.
Spherocylindrical Lenses
16. A sphero-cylinder lens combines:
A. Two spheres
B. Sphere + cylinder
C. Two cylinders
D. Plano + sphere
View Answer
B. Sphere + cylinder ✅ Exp: Corrects sphere + astigmatism.
17. Prescription: –2.00 DS / –1.00 DC × 180 means:
A. Sphere –2, Cylinder –1, Axis 180
B. Sphere –1, Cylinder –2
C. Sphere +2, Cylinder –1
D. Cylinder only
View Answer
A. Sphere –2, Cylinder –1, Axis 180 ✅ Exp: Standard notation.
18. +1.00 DS / –2.00 DC × 90 is equivalent to:
A. –1.00 DS / +2.00 DC × 180
B. +1.00 DS / +2.00 DC × 90
C. –2.00 DS / –1.00 DC × 180
D. +3.00 DS only
View Answer
A. –1.00 DS / +2.00 DC × 180 ✅ Exp: Cylinder transposition rule.
19. Crossed cylinders are used for:
A. Correction of spherical errors
B. Astigmatism testing
C. Presbyopia correction
D. Myopia correction only
View Answer
B. Astigmatism testing ✅ Exp: Cross cylinder test refines axis/power.
20. Cylindrical lenses produce distortion of:
A. Image size
B. Image shape
C. Chromatic colors
D. Binocular vision
View Answer
B. Image shape ✅ Exp: Cylinder stretches image in one axis.
Lens Aberrations
21. Spherical aberration is minimized by:
A. Using aspheric lenses
B. Increasing curvature
C. Reducing refractive index
D. Thickening the lens
View Answer
A. Using aspheric lenses ✅ Exp: Aspheric surfaces control aberrations.
22. Chromatic aberration occurs because:
A. Different wavelengths refract differently
B. Uneven curvature
C. Accommodation
D. Prisms in lens
View Answer
A. Different wavelengths refract differently ✅ Exp: Dispersion of light causes it.
23. Which lens material reduces chromatic aberration?
A. High Abbe number
B. Low Abbe number
C. High refractive index only
D. Plastic lens
View Answer
A. High Abbe number ✅ Exp: High Abbe → less dispersion.
24. Coma aberration is:
A. Off-axis point source appears comet-shaped
B. Blur due to multiple foci
C. Unequal magnification
D. Peripheral distortion only
View Answer
A. Off-axis point source appears comet-shaped ✅ Exp: Coma affects off-axis points.
25. Distortion in high plus lenses appears as:
A. Pincushion
B. Barrel
C. Spherical
D. Coma
View Answer
A. Pincushion ✅ Exp: + lenses → pincushion distortion.
Lens Form & Spectacle Design
26. Distortion in high minus lenses:
A. Pincushion
B. Barrel
C. Spherical
D. Astigmatic
View Answer
B. Barrel ✅ Exp: – lenses → barrel distortion.
27. Base curve in spectacle lenses refers to:
A. Front surface curvature
B. Back surface curvature
C. Lens thickness
D. Optical center
View Answer
A. Front surface curvature ✅ Exp: Standardized for consistency.
28. High index lenses have:
A. Thicker edge in minus lenses
B. Thinner edge in minus lenses
C. Thicker center in plus lenses
D. Poorer optics always
View Answer
B. Thinner edge in minus lenses ✅ Exp: High n reduces thickness.
29. Aphakic spectacles cause:
A. Ring scotoma (jack-in-the-box)
B. Barrel distortion
C. Pincushion distortion
D. Diplopia
View Answer
A. Ring scotoma (jack-in-the-box) ✅ Exp: Edge magnification causes ring scotoma.
30. Aphakic spectacles cause image magnification of about:
A. 5%
B. 15–20%
C. 25–30%
D. 40%
View Answer
B. 15–20% ✅ Exp: Magnification ~25% with +10–12 D, but 15–20% clinically significant.
31. Cylindrical lenses are used in keratoconus correction:
A. Always
B. Only in mild cases
C. Never
D. Only surgical
View Answer
B. Only in mild cases ✅ Exp: Early keratoconus corrected with cylinders; advanced needs RGP lenses.
32. Toric lenses are:
A. Cylindrical lenses
B. Sphero-cylindrical lenses
C. Plano-concave lenses
D. Meniscus only
View Answer
B. Sphero-cylindrical lenses ✅ Exp: Toric lenses = sphere + cylinder, used in astigmatism.
33. In spectacles, decentration of lens induces:
A. Prism effect
B. Aberration only
C. Astigmatism
D. Accommodation
View Answer
A. Prism effect ✅
34. Prentice’s rule:
A. P = cF
B. P = n/f
C. P = (n–1)(1/R₁ – 1/R₂)
D. P = 1/f
View Answer
A. P = cF ✅ Exp: Prism = decentration × lens power.
35. In cylindrical lenses, meridian of maximum power is:
A. Along axis
B. 90° to axis
C. Parallel to axis
D. Random
View Answer
B. 90° to axis ✅ Exp: Cylinder acts perpendicular to axis.
36. A +2 D sphere combined with –2 D cylinder at 180° gives correction for:
A. Simple hypermetropic astigmatism
B. Compound hypermetropic astigmatism
C. Mixed astigmatism
D. Myopia only
View Answer
C. Mixed astigmatism ✅ Exp: One meridian +, other –.
37. A plano lens combined with +2 D cylinder at 90° corrects:
A. Simple hypermetropic astigmatism
B. Simple myopic astigmatism
C. Mixed astigmatism
D. Presbyopia
View Answer
A. Simple hypermetropic astigmatism ✅ Exp: Only one meridian hypermetropic.
38. A plano lens combined with –2 D cylinder at 90° corrects:
A. Simple myopic astigmatism
B. Compound myopia
C. Mixed astigmatism
D. Presbyopia
View Answer
A. Simple myopic astigmatism ✅ Exp: Only one meridian myopic.
39. Compound hypermetropic astigmatism correction:
A. Both meridians need + power
B. Both meridians need – power
C. One plus, one minus
D. No correction
View Answer
A. Both meridians need + power ✅ Exp: Both focus behind retina.
40. Compound myopic astigmatism correction:
A. Both meridians need – power
B. Both meridians need + power
C. One plus, one minus
D. Cylinder only
View Answer
A. Both meridians need – power ✅ Exp: Both meridians focus in front of retina.
