Associations of antioxidant enzymes with cataract and age-related macular degeneration: The POLA study

Abstract

Objective Oxidative mechanisms may play an important role in the etiology of cataract and age-related macular degeneration (AMD). The authors present the level of two antioxidant enzymes in relation to cataract and AMD. Design Population-based, cross-sectional study on cataract and AMD and their risk factors. Participants This study includes 2584 participants recruited among the residents of the town of Sète (in the south of France), who were 60 years of age or older. Intervention/methods Cataract was defined on the basis of slit-lamp examination, according to the Lens Opacities Classification System III, and AMD on the basis of fundus photographs according to an international classification. Biologic measurements were made centrally from blood samples for which the patient fasted. Main outcome measures The presence of early and late AMD and of subcapsular, cortical, nuclear, and mixed cataracts was assessed and related to the levels of plasma glutathione peroxidase and erythrocyte superoxide dismutase. Results After multivariate adjustment, higher levels of plasma glutathione peroxidase (plGPx) were significantly associated with a ninefold increase in late AMD prevalence, a sixfold increase in cortical cataract, and a twofold increase in nuclear and mixed cataracts. High levels of erythrocyte superoxide dismutase (SOD) activity were not associated with late AMD and early signs of AMD but were associated with a twofold increase in nuclear cataract. Conclusion The authors show here, for the first time, a strong association of high levels of plGPx with age-related eye diseases. High levels of SOD also are associated with increased risk of nuclear cataract. More data are needed at the biochemical and epidemiologic levels for a better understanding of these findings.