Presbyopia or tired eyesight occurs when you can't see close objects. It’s common in people over 40 years old.

Consequently, light rays focus at a point behind the retina, rather than directly on its surface. It’s similar to hyperopia , but the causes are different, so it’s called “adult hyperopia”.

The factors which cause presbyopia are convergence, accommodation and myosis. These three factors occur together resulting in short-sight.  

The causes are related to the loss of flexibility of the lens, aging of the lens or because the ciliary muscle is loose.