Presbyopia

A normal lens is elastic at birth. Because of its elastic property, it can be spherically adapted for the accommodation of the lens to focalize at different distances. The lens needs most accommodation for near distances.

Because a child has a very flexible lens, it can see things very close to the eye sharply. The older we get, the more the lens loses its elasticity and accommodation will be reduced. Therefore, we must look at things farther away from the eye, so we can still see sharply. Usually, sometime between the age of 40 and 60, our arms are not long enough to be able to read without glasses. This situation is called presbyopia. This is the time when a normal eye requires reading glasses.