Question

Which type of lenses are prescribed for the correction of astigmatism of human eye?

• A. convex
• B. plane
• C. concave
• D. cylindrical

Answer 1

Answer:

D. cylindrical

Cylindrical lenses are prescribed for the correction of astigmatism in the human eye.

Astigmatism occurs when the cornea or lens of the eye has an irregular, asymmetrical curvature (shaped more like a football than a basketball). This causes light rays to focus on multiple points instead of a single focal point on the retina, resulting in distorted or blurry vision.

• How it works: Unlike regular spherical lenses (which bend light equally in all directions), a cylindrical lens focuses light along a single meridian (axis). This specific orientation compensates for the uneven curvature of the eye to focus all light perfectly onto the retina.

Quick Comparison of Eye Defects & Corrections:

Eye Defect	Common Name	Type of Lens Used
Astigmatism	Asymmetrical vision	Cylindrical lens
Myopia	Nearsightedness	Concave lens
Hypermetropia	Farsightedness	Convex lens
Presbyopia	Age-related vision loss	Bifocal lens