Question

Name the type of lenses required by the persons for the correction of their defect of vision called presbyopia. Write the structure of the lenses commonly used for the correction of this defect giving reason for such designs.

Hint:

Bifocal lenses are commonly used by people with presbyopia because they correct both near and distant vision.

Answer 1

Lenses for Presbyopia: To correct presbyopia, either bifocal lenses or progressive lenses are employed.
Bifocal Lens Design: Bifocal lenses have two sections: the bottom for close-up viewing and the top for seeing far away. Usually, the bottom part is a convex lens, assisting with near vision, while the top part is a concave lens, facilitating distance vision. 
The purpose of bifocal lenses is to correct both near and far vision without needing to switch eyeglasses.