Purpose: To describe the 5-year cumulative incidence and change in epiretinal membranes in a defined older Australian population.
Design: Population-based cohort study.
Participants: Three thousand six hundred fifty-four persons 49 years of age or older, living in the Blue Mountains area, west of Sydney, Australia, participated in the baseline survey during 1992 to 1994. The cohort was reexamined after 5 years in 1997 to 1999. Excluding persons (543) who died since the baseline, 75% of survivors (n = 2335) attended the follow-up examination.
Methods: All participants underwent a detailed eye examination, including stereo retinal photography. Epiretinal membranes were diagnosed from grading of baseline and 5-year retinal photographs.
Main outcome measures: Epiretinal membranes were classified as either preretinal macular fibrosis (PMF), with retinal folds, or as a less severe form, termed cellophane macular reflex (CMR), without retinal folds. The incidence of epiretinal membranes was determined if either lesion was found in eyes with no preexisting epiretinal membrane at baseline. Progression was defined if the area of involvement increased by more than 25%, regression if it decreased by more than 25%, and stable if it changed by less than 25%.
Results: Epiretinal membranes developed in the first eye of 108 of 2030 participants who had no sign of this condition in either eye at baseline, 5.3%, 95% confidence interval (CI) 4.4 to 6.4. Five-year cumulative incidence rates for PMF and CMR were 1.5% and 3.8%, respectively. Of those participants with epiretinal membranes in one eye at baseline, 18 of 133 (13.5%) developed this sign in their second eye after 5 years. New epiretinal membranes (mostly CMR) occurred in 15 of 165 subjects (9.1%; CI, 5.2-14.6) who had undergone cataract surgery since the Blue Mountains Eye Study I. This rate was significantly higher than in the nonsurgical group, 92 of 1861 (4.9%; CI, 4.0-6.0) of whom developed epiretinal membranes. Progression from CMR to PMF was observed in 17 of 183 eyes (9.3%). Existing epiretinal membranes progressed, regressed, or remained stable in 28.6%, 25.7%, and 38.8% of eyes, respectively.
Conclusions: This study has documented the 5-year cumulative incidence and the natural history of epiretinal membranes in an older population.