What is meant by power of accommodation of the eye?
The power of accommodation of the eye refers to the ability of the eye lens to adjust its focal length to see objects clearly at different distances. This adjustment is made possible by the ciliary muscles which modify the curvature of the eye lens.
When the ciliary muscles are relaxed, the lens becomes thin, its focal length increases, and we can see distant objects clearly. When looking at nearby objects, the ciliary muscles contract, the lens becomes thicker, its curvature increases, and the focal length decreases, enabling us to see nearby objects clearly.
However, the focal length of the eye lens cannot be decreased below a certain minimum limit. The power of accommodation usually decreases with ageing.
Explanation
This answer is based directly on Section 10.1.1 of the NCERT textbook which defines accommodation and explains how the ciliary muscles control the curvature and focal length of the eye lens. The textbook explicitly states that 'The ability of the eye lens to adjust its focal length is called accommodation.' It also mentions that this power decreases with ageing (Presbyopia).