Iris Color, Skin Sun Sensitivity, and Age-related Maculopathy. The Blue Mountains Eye Study

Objective: The purpose of the study was to assess relationships between age-related maculopathy (ARM) and iris color, skin sun sensitivity, and other sunlight-related factors.

Design: Cross-sectional population-based study.

Participants: The Blue Mountains Eye Study performed a detailed eye examination of 3654 residents living in the Blue Mountains area, west of Sydney, Australia.

Main Outcome Measures: Subjects with late age-related macular degeneration (late AMD), early ARM, and large drusen (> or = 125 microns diameter) were identified using masked grading of retinal photographs. Iris color was graded using standard photographs, and interviewers collected questionnaire data on sunlight-related factors. Logistic regression, adjusting for age, sex, AMD family history, and current smoking, was used to assess associations.

Results: Blue iris color was significantly associated with an increased risk of both late AMD (odds ratio [OR], 1.69) and early ARM (OR, 1.45). An increased risk of late AMD, but not early ARM, was associated with both high (OR, 2.54) and low (OR, 2.18) skin sun sensitivity, as assessed using the Fitzpatrick sun-sensitivity scale. These associations remained after adjusting for the presence of sun-related skin damage. Neither history (or treatment) of skin cancer lesions, signs of sun-induced skin damage, or number of severe sunburns was associated with either late AMD or early ARM.

Conclusions: Blue iris color was associated with an increased risk of both late AMD and early ARM in this population. Abnormal skin sensitivity to sunlight was also associated with an increased risk of late AMD.