Question

The ability of eye to focus on both near and far objects is called:
(A) Presbyopia
(B) Myopia
(C) Hypermetropia
(D) Power of accommodation

Answer 1

Hint:
The muscles in our eye can adjust the focus of the lens present in our eye to focus on different objects at different times at different distances. Due to this ability, our eye can focus on near as well as far away objects, and this ability is called the power of accommodation.

Complete step by step answer:
The human eye is a very unique organ. It has a highly useful ability to adjust the focal length of the eye by changing the shape of the lens. The ciliary muscles in the eye push or pull the lens to change its shape.
When the object is placed nearby, then the ciliary muscles contract and hence on doing that squeezes the lens into a more convex shape. This increases the curvature of the lens and decreases the focal length of the lens.
Again when there is an object present at a distance then the ciliary muscles relax, thereby making the lens flatter. This decreases the curvature of the lens and hence increases the focal length of the lens.
This whole function is done by our eye automatically and instantaneously.
And this ability of the eye is termed as the power of accommodation.
Therefore, the correct answer is option (D).

Note:
A healthy eye has a huge range of focus and can do so without the need for any corrective lens. The power of accommodation of a healthy eye is about 4 diopters. As the age of a person increases, the power of accommodation of the eye decreases as they are not able to focus on the nearby objects.