Also known as age sight degradation, presbyopia occurs when the elasticity of the eye lenses become increasingly staler and weaker as a result of ageing.
Eyes focus normally on distance further away. However, the lenses of the eyes tend to press together when focusing on something nearby. This becomes all the more difficult when the eyes lose their elasticity due to old age. It means that the eye experiences more difficulty when sharply focusing on nearby objects, a typical result of age sight degradation. It normally begins to develop in your 40s and becomes steadily worse, eventually demanding the use of reading glasses or bi-focal contact lenses.
Evidence of this can be experienced when one is forced to hold newspapers and books further away from oneself in order to read them. Short sighted people very often have to remove contact lenses or spectacles to enable them to read at normal distances.