Macular degeneration is a deterioration of the central portion of the retina that causes poor central vision, and is the leading cause of impaired reading or detailed vision. Although macular degeneration causes distortion of central and color vision, side vision is not affected. Macular degeneration is often a natural result of the aging process and is most common in people over 60, but can appear as early as age 40. Occasionally, macular degeneration is caused by injury, infection, or inflammation. The disease may also be hereditary.