The gradual loss of the eye's accommodation as a person ages is a natural process called presbyopia. This condition becomes noticeable between 40 and 50 years of age. It is marked by increased difficulty in bringing near objects into focus.
With presbyopia the lens loses the flexibility that characterizes a young eye. The firmer the lens, the more difficulty it has changing its shape to focus on near objects. Those who have their refractive problem corrected can still expect to experience presbyopia as their eye ages. One modern solution to presbyopia might be a lens replacement with a multi-focal lens implant.