Question

What is the minimum distance of distinct vision for a normal human eye?

Hint:

The minimum distance of distinct vision is an important factor in determining whether a person needs corrective lenses for close-up tasks, like reading.

Answer 1

The minimum distance of distinct vision, also known as the near point, is the closest distance at which a normal human eye can focus on an object clearly and without strain. For a healthy adult eye, this distance is conventionally taken to be 25 cm. At this distance, the ciliary muscles contract to make the eye lens as convex as possible, allowing it to focus the image of the object sharply onto the retina. If an object is brought closer than this distance, the eye cannot increase the curvature of the lens any further, and the image appears blurred.