The Incidence and Progression of Age-Related Macular Degeneration over 15 Years: The Blue Mountains Eye Study

Purpose: To assess the 15-year incidence and progression of age-related macular degeneration (AMD) in an older Australian population.

Design: Population-based cohort study.

Participants: Blue Mountains Eye Study (BMES) participants (n = 3654) aged 49+ years were examined during 1992-1994. Of these, 2334 (75.8% of survivors) were reexamined after 5 years (1997-1999), 1952 (76.7% of survivors) after 10 years (2002-2004), and 1149 (56.1% of survivors) after 15 years (2007-2010).

Methods: Color retinal photographs were taken, and comprehensive questionnaires were administered at each visit and DNA was genotyped. Retinal photographic grading was performed by the same graders following the Wisconsin AMD grading protocol. Side-by-side comparisons were used to confirm newly developed AMD lesions. Incidence was estimated using Kaplan-Meier estimates. Associations of AMD incidence with age, sex, smoking status, presence of the complement factor H (CFH)-rs1061170 and age-related maculopathy susceptibility 2 (ARMS2)-rs10490924 polymorphisms, and fish consumption were analyzed using discrete logistic regression models. Generalized estimation equation models were used to assess the risk of incident late AMD associated with baseline AMD lesion characteristics.

Main outcome measures: The 15-year incidence and progression of AMD, and associated factors.

Results: The 15-year incidence was 22.7% for early AMD and 6.8% for late AMD. After adjusting for competing risks, early and late AMD incidence were 15.1% and 4.1%, respectively. Age was strongly associated with early and late AMD incidence (both P < 0.0001). After age standardization to the Beaver Dam Eye Study (BDES) population, early and late AMD incidence in the BMES were 13.1% and 3.3%, respectively. Female sex and the presence of both risk alleles of CFH-rs1061170 or ARMS2-rs10490924 were independently associated with early AMD incidence, whereas current smoking and presence of ≥1 risk allele of CFH-rs1061170 or ARMS2-rs10490924 were associated with late AMD incidence. Fish consumption was inversely associated with late but not early AMD incidence. Severity of early AMD lesion characteristics was a strong predictor of progression to late AMD.

Conclusions: We documented the 15-year incidence of early and late AMD in an older Australian population that were comparable to BDES observations. Risk of progression to late AMD was strongly associated with severity of early AMD lesions.