Long-term natural history of idiopathic epiretinal membranes with good visual acuity

Background/objectives To evaluate the long-term progression of idiopathic epiretinal membranes (iERMs) with good baseline visual acuity, and to identify predictors of visual decline. Design Retrospective case series Subjects methods We reviewed records of 145 eyes with iERM and best-corrected visual acuity (BCVA) of 20/40 or greater at presentation, including BCVA, lens status, and central macular thickness (CMT) at yearly visits; as well as anatomic biomarkers including vitreomacular adhesion, pseudohole, lamellar hole, intraretinal cysts, disorganization of the inner retinal layers (DRIL), and disruption of outer retinal layers. Linear mixed effects and mixed-effects Cox proportional hazards models were used to identify clinical and anatomic predictors of vision change and time to surgery. Results At presentation, mean BCVA was 0.17 +/- 0.10 logMAR units (Snellen 20/30) and mean CMT was 353.3 +/- 75.4 mu m. After a median follow-up of 3.7 years (range 1-7 years), BCVA declined slowly at 0.012 +/- 0.003 logMAR units/year, with phakic eyes declining more rapidly than pseudophakic eyes (0.019 +/- 0.003 vs. 0.010 +/- 0.004 logMAR units/year). Metamorphopsia, phakic lens status, lamellar hole, and inner nuclear layer cysts were associated with faster visual decline. Cumulative rates of progression to surgery were 2.9, 5.6, 12.2, and 21.1% at years 1-4. Visual symptoms, metamorphopsia, greater CMT, and disruption of outer retinal layers were associated with greater hazard for surgery. Conclusion Eyes with iERM and visual acuity >= 20/40 experience slow visual decline, with 21% of eyes requiring surgery after 4 years. Clinical and anatomic predictors of vision loss may be distinct from factors associated with earlier surgical intervention.