Question

For the myopic eye, the defect is cured by

• A. Convex lens
• B. Concave lens
• C. Cylindrical lens
• D. Toric lens

Answer 1

Answer: (B)

Myopia is a vision condition, in which a person can see nearby objects clearly but objects farther away appear blurry. Hence the far point of the eye is reduced.

So to cure this , we should use a lens of focal length $f$ such that it forms the image of objects at infinity at the distance of the far point of the person.

Hence, applying the lens' formula

In myopia, $u=\infty ,v=-d=$ distance of far point
By $\frac{1}{F}=\frac{1}{v}-\frac{1}{u}$, we get $f=-d$
Since f is negative, hence the lens used is concave.