Presbyopia is caused by an age-related process. It typically affects people around age 40 where people experience blurred vision at near points, such as when reading, sewing or working at the computer. This is different from astigmatism, nearsightedness and farsightedness, which are related to the shape of the eyeball and caused by genetic factors, disease or trauma. Presbyopia is generally believed to stem from a gradual loss of flexibility in the natural lens inside the your eye.
These age-related changes occur within the proteins in the lens, making the lens harder and less elastic with the years. Age-related changes also take place in the muscle fibers surrounding the lens. With less elasticity, the eye has a harder time focusing up close.
The amount of power that is needed in glasses to correct for presbyopia is dependent on the strength of the glasses needed for distance vision. For persons who are nearsighted, removal of the glasses may make it easier to read up close. For those not nearsighted, glasses or bifocals are needed to see well up close. A complete eye examination will determine the strength of lenses needed to see well at all distances. Contact lenses are also an option to correct presbyopia.