Abstract
Purpose: :
To examine the association between iris, skin or hair colour, 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 (1992–4, 82.4% participation rate). 2335 participants were re–examined (75.1% of survivors) after 5–years (1997–9) and 1952 (76.5% of survivors) after 10–years (2002–4). Retinal photographs were graded using the Wisconsin ARM Grading System and incident ARM confirmed using side–by–side grading method. Iris, skin and hair colour, and sun–related skin damage were assessed and skin sun–sensitivity questions were asked at baseline. The 10–year ARM incidence was calculated using Kaplan Meier methods and discrete logistic model was used to assess the association after adjusting for age, sex and smoking.
Results: :
Incidence rates for late and early ARM among participants with different iris colours were: blue, 3.3%, 13.2%; hazel/green, 2.5%, 9.8%; brown, 1.7%, 10.3% and dark–brown, 4.6%, 12.6%, respectively. Persons with very fair skin colour had a higher incidence of both late and early ARM (7.1%, 16.2%) compared to persons with fair (2.6%, 11.5%), light olive (3.0%, 10.9%) and dark skin colour (2.6%, 14.1%). Incidence rates among persons with different skin sun sensitivity were ranged from 1.4% to 4.9% for late and 10.7% to 14.1% for early ARM. Corresponding incidence rates for persons with different levels of sun–related skin damage ranged from 2.7% to 4.2% for late and from 10.8% to 14.6% for early ARM. After adjustment, no significant associations were found between iris or hair colour and late or early ARM incidence. Compared to persons with fair skin, those with very fair skin had an increased risk of developing geographic atrophy (multivariate adjusted risk ratios, RR 7.6; 95% confidence interval, CI, 3.0–19.6). In contrast, compared to persons with average skin sun sensitivity, persons who said that their skin would usually burn and tan with difficulty had a reduced risk of neovascular ARM (RR 0.2, CI 0.0–0.7). Sun–related skin damage was not associated with incident 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.
Keywords: age-related macular degeneration • clinical (human) or epidemiologic studies: risk factor assessment • clinical (human) or epidemiologic studies: prevalence/incidence