The role of ocular free radicals in age-related macular degeneration

Abstract

Age-related macular degeneration (AMD), the leading cause of irreversible blindness in the western world, is a major ocular public health problem of increasing concern, especially in light of the world’s rapidly growing elderly population. It is a particularly frustrating disease for ophthalmologists and their patients due to its relentless progressive course, which can ultimately lead to legal blindness. For the vast majority of patients, there are no proven interventions that can halt or reverse the damage wrought by the disease. Since treatment options in the late stages of AMD are so limited, there is considerable interest in identifying modifiable environmental risk factors that in turn could be used to guide early intervention strategies to lessen the risk of visual loss from AMD in susceptible individuals. As will be discussed below, there is substantial evidence that retinal pathology due to AMD is in part mediated by oxidative damage to photoreceptors and other ocular cells. The possibility that individuals can modulate their risk of visual loss from AMD by decreasing their exposure to environmental oxidants or by increasing their dietary consumption of antioxidants has been enthusiastically embraced by many members of the ophthalmic community, by the nutraceutical industry, and by the general public. The scientific basis to support these interventions, however, often lags behind the popular wisdom. In this chapter, the pathogenesis of AMD will be reviewed, the possible mechanisms for free radical