Name the delicate membrane in the eye having an enormous number of light-sensitive cells.

An old person is unable to see clearly nearby objects as well as distant objects. $(i)$ What defect of vision is he suffering from? $(ii)$ What kind of lens will be required to see clearly the nearby as well as distant objects? Give reasons.

$A$ person with defective vision is unable to see objects nearer than $1.5 \ m$. He wants to read books at a distance of $30 \ cm$. Find the nature, focal length, and power of the lens he needs in his spectacles.

When do we consider a person to be myopic or hypermetropic? Explain how the defects associated with a myopic and hypermetropic eye can be corrected.

Through which part of the eye do light rays from an object first enter the eye?

Name the condition resulting due to the eye lens becoming cloudy.