Question

Due to gradual weakening of ciliary muscles and diminishing flexibility of the lens a certain defect of vision arises. Write the name of this defect . Name the type of lens required by such persons to remove the vision. Explain the structure and function of such a lens.

Answer 1

Name of this defect is Presbyopia.

In this case Bifocal lens is used.

Structure :

Bifocal lens consist of both concave and convex lens. In the upper portion of lens concave lens is used and in the other half convax lens is used.

Function :

In the human eye, the function of the Bifocal lens is to focus the light rays entering the eye from an object and form a real and inverted image of the object on the light-sensitive screen called the retina.