Presbyopia
With presbyopia, the natural lens of the eye begins to harden and becomes less flexible. This diminishes the eye’s ability to switch its focus from one object to another at different distances. Over time while distance vision may be very good near vision gets progressively worse. Presbyopia usually occurs before cataracts and affects almost everyone over 50. Eventually reading glasses or bifocals become necessary for reading, and frequent changes in eyeglass prescriptions are common.