Purpose
To assess 15-year incidence of reticular drusen (RDR) and their associations with known age-related macular degeneration (AMD) risk factors in an older Australian cohort.
Methods
The Blue Mountains Eye Study examined 3654 participants aged 49+ years at baseline (1992-94), and re-examined 75.8, 76.5 and 56.1% of survivors 5, 10 and 15 years later, respectively. Retinal photographs were taken at each visit and DNA samples genotyped. Incidence and progression of RDR were confirmed using side-by-side grading from colour photographs. Incidence was estimated using the Kaplan-Meier product-limit survival method, controlling for competing risk of death. Associations between incidence of RDR and smoking, fish consumption, serum lipids, white cell count, and CFH-rs1061170 and ARMS2-rs10490924 single nucleotide polymorphisms were analyzed using discrete logistic regression models adjusting for age and sex.
Results
The 15-year cumulative incidence of RDR was 4.0% (n=95); increasing from 0.4% in the age group 49-54 years to 7.0% in those aged 65-74 years, and then decreasing to 4.9% in those aged 75+ years (P for trend <.0001). Women had a higher incidence of RDR compared to men (5.6% versus 2.2%, P=0.003). Increasing age (per decade; odds ratio, OR, 3.4; 95% confidence interval, CI, 2.6-4.4), female sex (OR 2.0, 95% CI 1.3-3.2) and presence of each risk allele of CFH (OR 1.8, 95% CI 1.3-2.4) or ARMS2 (OR 3.0, 95% CI 2.1-4.4) were associated with increased risk of developing RDR. Baseline current smokers had a significantly higher risk of RDR (OR 2.1, 95% CI 1.0-4.5) after adjusting for age, sex, and CFH and ARMS2 polymorphisms. Of 218 eyes with RDR (prevalent and incident cases), 40 eyes (18.4%) developed late AMD in 5 years (neovascular AMD 42.5%; geographic atrophy 57.5%). Total area of RDR or RDR extending to a near central location was found not to be associated with progression to late AMD in 5 years. A higher proportion of eyes with RDR located outside the macular area progressed to late AMD (36.4%), compared to those with RDR involving the macula area (10.1 and 22.2% for RDR within inner and outer subfields of the Wisconsin Grading grid, respectively).
Conclusions
Known AMD risk factors were associated with increased long-term risk of developing RDR. RDR area and location were not associated with progression to late AMD over 5 years.
Keywords: 504 drusen •
412 age-related macular degeneration •
463 clinical (human) or epidemiologic studies: prevalence/incidence