Question

The least distance of distinct vision is about for a healthy adult.

Answer 1

The least distance of distinct vision is the shortest distance at which objects may be viewed clearly without exertion.

1. It's also known as the eye's near point.
2. The near point for a young adult with normal eyesight is around $25cm$ $\left(0.25m\right)$.

Hence, the least distance of distinct vision is about $25cm$ for a healthy adult.