Visual acuity outcomes following surgery for idiopathic epiretinal membrane: an analysis of data from 2001 to 2011

Abstract

Pars plana vitrectomy (PPV) is commonly used to remove the epiretinal membrane (ERM), but the timing of surgical intervention guided by visual acuity (VA) performance at presentation is uncertain. Prospectively entered clinical data of 237 patients on an electronic patient record from 2001 to 2011 were analysed to determine visual outcomes, in particular in relation to pre-operative VA. The mean age of the patients was 68.8 years and 54.4% were female. Median follow-up was 0.55 years. The median pre-operative logMAR VA was 0.60 (SD 0.48-0.78, Snellen equivalent 6/36) and post-operative VA was 0.30 (SD 0.18-0.60, 6/12, P<0.005). Pre-operative VA correlated with post-operative VA (linear R(2)=0.22, P<0.0001). In all, 69.6% of patients showed an improvement in VA, 15.2% showed no change, and the condition of 15.2% worsened. The number of patients with an improvement in logMAR VA of more than 0.3 was greatest in those who had a pre-operative VA of 1.0 (6/60) or worse, followed by those in the range of 0.6-0.9 and then those with pre-operative VA of 0.5 or better (P<0.001). The proportion of patients with visual improvement of logMAR VA of more than 0.3 increased statistically with progressing years (P=0.019). In conclusion, this study shows improvement in VA after PPV and ERM removal. Patients with better initial VA achieve higher levels of visual outcome but those with poorer pre-operative VA show a greater change in VA following ERM surgery. Results of surgery improved over the time period of the study.