Question

Define the term power of accommodation. Write the modification in the curvature of the eye lens which enables us to see the nearby objects clearly.

Answer 1

1. The term ‘power of accommodation’ refers to the ability of the eye to focus the distant objects and the nearby objects on the retina by changing or adjusting the focal length (or converging power) of its lens with the help of ciliary muscles.
2. When the eye is focusing on a nearby object, the eye lens bulges and becomes thicker.
3. While focusing on a nearby object, the ciliary muscles of the eyes contract, loosening the suspensory ligaments attached to the eye.
4. Since these ligaments become loose, they stop pulling the eye lens, due to which the eye lens bulges under its own elasticity and becomes thick (or more convex) to increase its converging power.
5. Since the converging power increases, the thick eye lens can converge the diverging light rays coming from the nearby object to form an image on the retina.
6. When the eye is viewing a faraway object, the ciliary muscles relax and the lens becomes thinner.
7. The focal length of the eye lens increases and the image falls on the retina.