Abstract
Abstract: :
Purpose: Blue light photooxidative damage has been implicated in the etiology of age–related macular degeneration. This effect is potentially reduced within the fovea due to the presence of the xanthophylls zeaxanthin (Z) and lutein (L). The present study measured the protective effect of supplementation with Z and L against acute photochemical blue light exposure. Methods: Subjects were 8 rhesus monkeys with no lifelong intake of xanthophylls and no detectable macular yellow pigment, and 4 normal age–matched control animals fed stock diets. They received graded exposures (150 µm diameter) of 476 nm low–power laser energy within the fovea (0.5 mm (2.4o) eccentricity, just outside the peak macular pigment density) or within the parafovea (1.5 mm (7.2o) eccentricity). The xanthophyll–free animals were then supplemented with Z (OPTISHARPTM) or L in doses of 3.9 µmol/kg per day (equivalent to approximately 10–15 mg L or Z per animal and day) for 22–28 weeks and blue light exposures were repeated. Results: Foveae of control monkeys had significantly elevated photochemical damage thresholds compared to parafoveae (p=0.0050). In xanthophyll–free monkeys, thresholds in foveae and parafoveae were low and not significantly different (p=0.48); foveal thresholds in xanthophyll–free monkeys were lower than in control foveae (p=0.024) but similar to control parafoveae (p=0.55). After L or Z supplementation, foveal thresholds remained lower than in control animals (p=0.0375), but the sizes of supra–threshold lesions were significantly smaller than before supplementation (p=0.0001). Conclusions: Macular pigment in rhesus monkeys fed stock diets was associated with protection from blue light photochemical damage in the fovea compared with the parafovea, whereas monkeys lacking macular pigment showed no such foveal protection. Supplementation of xanthophyll–free monkeys with Z or L led to partial but statistically significant restoration of the foveal blue ligth protection.
Keywords: macular pigment • laser • carotenoids/carotenoid binding proteins