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.