Sunlight-related factors and the 10-year incidence of age-related maculopathy.

PURPOSE: To examine the associations among iris, skin, or hair color, and skin sun sensitivity and the 10-year incidence of age-related maculopathy (ARM).

METHODS: The Blue Mountains Eye Study (BMES) recruited 3654 participants aged 49+ years at baseline (1992-1994, 82.4% participation rate). Re-examinations of 2335 participants (75.1% of survivors) were done after 5 years (1997-1999) and 1952 (76.5% of survivors) after 10 years (2002-2004). Retinal photographs were graded using the Wisconsin ARM Grading System and incident ARM confirmed using the side-by-side grading method. Iris, skin, and hair color, and sun-related skin damage were assessed and skin sun-sensitivity questions were asked at baseline. Ten-year ARM incidence was calculated using Kaplan Meier methods and discrete logistic models were used to assess associations after adjusting for age, sex, and smoking.

RESULTS: After adjustment, no significant associations were found between iris or hair color and either late- or early-incident ARM. Compared to persons with fair skin, those with very fair skin had an increased risk of developing geographic atrophy (multivariate adjusted risk ratio, RR = 7.6; 95% confidence interval, CI = 3.0-19.6). In contrast, compared to persons with average skin sun sensitivity, persons who reported that their skin would usually burn and tan with difficulty had a reduced risk of neovascular ARM (RR = 0.2, 95% CI = 0.0-0.7). Sun-related skin damage was not associated with late or early ARM.

CONCLUSIONS: In this older cohort, we did not find a consistent pattern of association between sunlight-related factors and ARM incidence, except that persons with very fair skin might have an increased risk of geographic atrophy, consistent with our 5-year incidence data. The protective association between skin sensitivity to sun damage and neovascular ARM could have be the result of confounding by sun-avoidance behavior among persons sensitive to sunburn.