Association between sunlight exposure and risk of age-related macular degeneration: a meta-analysis

Abstract

BackgroundA substantial number of epidemiological studies have investigated the possible associations between sunlight exposure and Age-related Macular Degeneration (AMD), but the results from studies are inconsistent. The aim of this meta-analysis was to evaluate the association between sunlight exposure and the risk of AMD.MethodsRelevant studies were searched using databases including PubMed, EMBASE, and Web of Science database. Two authors independently extracted data and assessed study quality. The random-effects model was used to calculate the pooled covariates-adjusted odds ratio (OR). Subgroup analyses based on study design, stage of AMD, method of exposure assessment, and study latitude were carried out. The heterogeneity across the studies was tested, as was publication bias.ResultsFourteen eligible studies including 43,934 individuals based on the inclusion criteria were analyzed. The pooled OR for sunlight exposure and AMD was 1.10 (95% CI = 0.98–1.23). In addition, similar insignificant results were observed in further subgroup analyses based on stage of AMD, method of exposure assessment, and study latitude. Sun-avoidance behavior did not decrease the risk of AMD (OR = 1.12, 95% CI = 0.76–1.67). Moderate heterogeneity was observed in most of analyses.ConclusionThe results indicate that sunlight exposure may not be associated with increased risk of AMD based on current published data.

Quantifying Retinal Pigment Epithelium Dysmorphia and Loss of Histologic Autofluorescence in Age-Related Macular Degeneration

“…Collectively, our data with others indicate that contrary to widely held theories, L/ML may not be harmful in AMD. One theory suggests that L/ML are phototoxic, yet retinal illuminance is uniform well beyond the 21° diameter macula,76,77 and epidemiologic data do not support lifetime sunlight exposure as an AMD risk factor 78,79. This same theory builds on the deleterious effects of treating cultured cells with bisretinoid fluorophore A2E, yet this L/ML component is reliably lower in macula than in peripheral retina,43–48 a distribution not detectable in early studies analyzing whole eyecups 80.…”

Acute ultraviolet A exposure induces autophagy in RPE cells

“…Although many studies have demonstrated an association between UVA and AMD, there is still controversy. It was recently reported that sunlight exposure may not be a risk factor for AMD [37]. Therefore, it is necessary to elucidate the mechanisms of UVA irradiation effects on RPE cells.…”

Mitochondrial Dysfunction in the Aging Retina

“…Aging is a recognized factor that is associated with mitochondrial dysfunction in the outer retina. Other important risk factors for the development of AMD are genetics and environmental stressors, including smoking and exposure to ultraviolet and blue light [18,19,20,21,22,23,24]. All of these factors are likely to result in mtDNA damage in the RPE.…”

“…Although in vitro studies have unequivocally demonstrated that either UV or blue light damage RPE cells [22], epidemiological evidence of the association between exposure to sunlight and AMD is mixed [23]. The ability of the ocular media (cornea, lens, and vitreous humor) to block UV and blue light and the protection of the retina by antioxidant systems, including superoxide dismutase and glutathione peroxidase and macular pigments, including melanin and flavoproteins likely explain these differences [17].…”

“…The transfer of electrons generates a proton gradient across the mitochondrial intermembrane, which drives the synthesis of ATP by ATP synthase. During this process, small amounts of superoxide are produced, but the cell via antioxidant defense mechanisms easily clears them [20,21,22,23,24,25,26,27,28,29,30].…”