The exact mechanism is unknown however research suggests that the difficulty focusing on near objects come from the reduced elasticity and hardening of the crystalline lens along with the reduced strength in the cilliary muscles attached to the lens all stopping the lens from accommodating/focusing close up. This can cause two different optical corrections required in the eye, one for distance and one for near.
The first signs of presbyopia include eyestrain, problems reading in dim light and having to move small print further away to focus. This usually starts to occur between the ages of 40 and 50 and like wrinkles and grey hair, is a physiological symptom of ageing.
What you need to do
Presbyopia can be corrected by using spectacle and contact lens options. Spectacle options single vision in the form of reading glasses. Also if correction for distance and near is required, then we can use bifocal and varifocal lens options.
Contact lenses are becoming and increasingly popular way of treating presbyopia. Options for this include single vision contact lenses with reading glasses used, monovision, bifocal and varifocal contact lenses.