Figure 1.

Schematic sequence of damaging reactions. The sequence begins with either an oxidation, a photoxidation or a photosensitization event and ends with a damaging reaction resulting in a disease. It is proposed that oxidants and free radicals produced as a result of these initial events cause lipid peroxidation, the oxidation of critical bonds in proteins and DNA strand breaks. Cells possess an armory of protectants, including antioxidants and enzymes, that serve to quench the oxidants and free radicals, thereby minimizing the damage and the need for repair and replacement. In the case of light-dependent damage to ocular tissues, such as the retina in AMD, dark sunglasses will reduce exposure to sunlight.