Question

The eye defect astigmatism can be corrected by using a

• A. convex lens
• B. spherical lens
• C. plano-convex lens
• D. concave lens
• E. cylindrical lens

Hint:

Cylindrical lenses are specifically designed to correct astigmatism by compensating for the uneven curvature of the eye's lens or cornea.

Answer 1

Answer: (E)

Astigmatism is an eye condition where the cornea or lens has an irregular shape, causing blurred or distorted vision. This defect arises due to an uneven curvature of the eye's lens or cornea, which does not focus light onto a single point of the retina.
The best way to correct astigmatism is by using a cylindrical lens, which has different curvatures in different directions. A cylindrical lens helps to focus light properly and corrects the uneven focus caused by the irregular shape of the cornea or lens.
- Convex lens (A): A convex lens is used to correct farsightedness (hyperopia), not astigmatism.
- Spherical lens (B): A spherical lens is used to correct myopia or hyperopia but is not ideal for astigmatism.
- Plano-convex lens (C): This lens has one flat surface and one convex surface, but it is not specifically designed for correcting astigmatism.
- Concave lens (D): A concave lens is used for myopia (nearsightedness), not for astigmatism.
Thus, the correct answer is (E) cylindrical lens.