The family of sunlight-related eye diseases.

Five ocular disorders, independent clinical entities affecting different parts of the eye with distinctive histopathological features, are part of the same family of eye diseases because they share the same causal factors, of which the most important is molecular damage produced by sunlight. This family of eye diseases includes the major sources of impaired vision and blindness in our society, age-related cataract and age-related macular degeneration. Pterygium, photokeratitis, and cancer of peri-ocular skin are also sunlight-related eye diseases. In each condition, solar radiation, oxygen, and heat, acting in combination, are the primary causal factors. Analysis of the action spectra indicates that only the high-energy radiation in the solar spectrum, particularly the ultraviolet (UV), is hazardous to the eye. The evidence in support of these conclusions is summarized. It indicates that the risk of all sunlight-related eye diseases can be diminished by use of eyewear that absorbs the high-energy constituents of solar radiation during exposure to sunlight.