A Prospective Study of Binocular Visual Function before and after Successful Surgery to Remove a Unilateral Epiretinal Membrane

Objective: To examine the effect of a unilateral epiretinal membrane (uERM) on visual acuity, stereopsis, and motor fusion in patients before and after successful surgery to remove the membrane. Design: Cohort study. Participants: Twenty-seven consecutive patients undergoing surgery to remove an idiopathic uERM and 30 normal control subjects. Methods: Patients underwent full orthoptic examination before and between 3 and 6 months after surgery to remove a uERM. Stereoacuities were analyzed statistically using the Wilcoxon signed-rank test, Mann-Whitney U test, and Spearman correlation. Motor fusion ranges and visual acuities were compared using paired and unpaired t tests, with correlations examined by linear regression. Main Outcome Measures: Snellen visual acuity, TNO (stereoscopic acuity test of the Netherlands; Netherlands Organisation for Applied Scientific Research; Lameris Ootech BV, Nieuwegein, the Netherlands) and Titmus stereoacuity, motor fusion range. Results: Postoperative acuity and improvement in visual acuity after removal of a uERM were better in patients with a shorter duration of symptoms. Stereoacuity was substantially reduced in the presence of a uERM (TNO, P<0.001; Titmus, P<0.001; Mann-Whitney U test), as were total motor fusion ranges at near and distance (near P = 0.002; distance P = 0.015; t test). Stereoacuity was worse in patients with symptoms of longer duration (TNO, P = 0.21; Titmus, P = 0.045; Spearman rank correlation). After successful surgery, stereoscopic function improved. This improvement occurred mainly in those patients with better preoperative stereoacuity and a shorter duration of symptoms. Conclusions: Improvement in visual acuity after surgery was greater in patients with visual symptoms of shorter duration. A uERM adversely affected stereoscopic function, an effect that increased with time. The best monocular and binocular visual outcomes occurred in those patients who had earlier surgery. Financial Disclosure(s): The authors have no proprietary or commercial interest in any materials discussed in this article. Ophthalmology 2008; 115:1930-1937 (C) 2008 by the American Academy of Ophthalmology.