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

Type of Lenses: For the correction of presbyopia, bifocal lenses or progressive lenses are used. 
Structure and Reasoning: Bifocal lenses consist of two parts: a lower part for near vision and an upper part for distance vision. The lower part is typically a convex lens to aid in near vision, while the upper part is a concave lens to help with distance vision. 
The reason for using bifocal lenses is to correct the vision for both distant and near objects without changing glasses.