ISSN: 1300-0365
Dil: Türkçe
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Role Of Antioxidants And Oxidative Stress In The Ethiopathogenesis Of Age-related Macular Degeneration
Dr. Özlem YENİCE,a Dr. Sezen ÇAKIR,a Dr. Haluk KAZOKOĞLUa
aGöz Hastalıkları AD, Marmara Üniversitesi Tıp Fakültesi, İSTANBUL
Recently, oxidative stress has been implicated in the pathogenesis of age-related macular degeneration (AMD). Retina is very sensitive to oxidative stress. In eye, exposure to sun light is the most important mechanism for formation of oxygen radicals. Retina is one of the organs with highest metabolic activity and a common place for formation of oxygen radicals. Reactive oxygen mediatörs (ROM) may occur as the byproducts of cellular metabolism and photochemical reactions. Retina is an ideal environment fort the generation of reactive oxygen species for several reasons. Primarily, oxygen consumption by the retina is much greater than by any other tissue. Secondly, the retina is subject to high levels of cumulative irradiation. Third, photoreceptor outer segment membranes are rich in polyunsaturated fatty acids, which are readily oxidized and which can initiate a cytotoxic chain-reaction. Fourth, the neurosensory retina and the retina pigment epithelium (RPE) contain abundant number of photosensitizers. Additional to all these, the process of phagocytosis by the RPE is itself an oxidative stress and results in the generation of ROI. Oxidative damage to cells by free radicals is a widely accepted hypothesis for aging. According to this hypothesis, enzymes that destroy free radicals (superoxides and peroxides) as protect cells against age-related damage. Irreversible tissue damage caused by such oxidative processes accumulates in time which we observe the phenotypic changes of aging. Oxidative stress results in pathological changes in the presence of genetic and environmental risk factors. In retina there are some antioxidant mechanisms for protection against oxidative stress. Retina pigment epithelium which degrades free radicals and peroxides includes several enzymes including catalase and superoxide dismutase and antioxidant vitamins such as ascorbic acid (vitamin C), α-tocopherol (vitamin E) and carotenoids (lutein ve zeoxanthine).
We aimed to summarize all the mechanisms of antioxidation and present recent literature about vitamins and AMD.Keywords: Macular degeneration; antioxidants; vitaminsTurkiye Klinikleri J Ophthalmol 2007, 16:114-121
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