Cataract Surgery Outcomes in Eyes With Primary Epiretinal Membrane.

Importance: Primary epiretinal membrane (ERM) is a common retinal disorder with a prevalence of 4% to 18.5%. Although ERM and cataracts commonly occur together, to our knowledge, no studies have investigated the outcome of cataract surgery alone in this setting. Objective: To analyze the visual outcome and cystoid macular edema risk with cataract surgery in eyes with primary ERM. Design, Setting, and Participants: In this retrospective clinical database study, data were collected from July 2003 to March 2015 from 8 locations in the United Kingdom. Cataract surgery data of 217 557 eyes were extracted from the electronic medical record of the UK National Health Service. After exclusion of 57 561 eyes with combined surgery, prior vitrectomy, copathology, and complications, 812 eyes with primary ERM and 159 184 reference eyes were analyzed. Main Outcomes and Measures: We report on visual acuity (VA), the incidence of cystoid macular edema, and the need for ERM surgery. Results: The mean (SD) age of patients in the ERM group was 73.7 (9.23) years, and 395 of 812 were men (46.8%). The mean (SD) age of patients in the reference group was 74.4 (12.19) years, and 65 265 of 159 184 were men (41%). Epiretinal membrane eyes assessed at 4 to 12 weeks postoperatively gained 0.27 (0.32) logMAR (approximately 3 Snellen lines), with 200 of 448 (44.6%) improving by 0.30 logMAR or more (≥3 Snellen lines) and 32 of 448 (7.1%) worsening by 0.30 logMAR or more. Reference eyes gained a mean (SD) of 0.44 (0.26) logMAR (approximately 4 Snellen lines), with 48 583 of 77 408 (62.8%) improving by 0.30 logMAR or more and 2125 of 77 408 (2.7%) worsening by 0.30 logMAR or more. Although all eyes with preoperative VA of 20/40 or less improved, only reference eyes with preoperative VA of more than 20/40 showed improvement. Cystoid macular edema developed in 57 of 663 ERM eyes (8.6%) (95% CI, 6.69-10.98) and 1731 of 125 435 reference eyes (1.38%) (95% CI, 1.32-1.45) (P < .001). Epiretinal membrane surgery was performed in 43 of 663 (6.5%) ERM eyes. Conclusions and Relevance: On average, VA improved 0.27 logMAR (approximately 3 Snellen lines) in eyes with ERM. Eyes with ERM and VA of 20/40 or less showed more benefit after cataract surgery than those with better preoperative vision. However, compared with eyes without ERM, higher rates of cystoid macular edema and a lower postoperative VA gain were noted.