Presbyopia is an eye condition in which the lens loses the ability to focus over time. It then becomes difficult to see small objects, especially close up.
Accommodation is the ability of the lens in the eye to adjust itself for focusing close up. The lens changes from a flat, thin state to a thicker, more curved state to allow a person to see a distant object versus a closer one. In individuals with presbyopia, the lens becomes less flexible. Presbyopia is a natural part of the aging process.
Presbyopia usually begins in people starting at about age 45. Normal aging causes changes in the eye that lead to problems with focusing. Only in rare cases is this condition related to other factors. Trauma and certain diseases, especially a contagious disease called diphtheria, may weaken the muscles in the eye.