Outer retinal morphological changes and visual function after removal of epiretinal membrane

Objective: To determine the relation between the recovery of the cone outer segment tips (COST) line and the best-corrected visual acuity (BCVA) after epiretinal membrane (ERM) surgery. Design: Retrospective, consecutive, interventional case series. Participants: Sixty-one eyes of 56 patients with an idiopathic ERM were studied. All participants underwent a complete ophthalmic examination including spectral-domain optical coherence tomography before and after ERM removal surgery. Methods: The integrities of the photoreceptor layer including the external limiting membrane line, photoreceptor inner segment/outer segment (IS/OS) line, and COST line in the spectral-domain optical coherence tomography images at the fovea were determined. The associations of these morphological parameters to the BCVA were determined. Results: Better BCVAs were found more frequently in eyes with an intact COST line than in eyes with a disrupted or absent COST line at 1 (p < 0.001), 6 (p = 0.003), and 12 months (p < 0.001). Among the external limiting membrane, IS/OS, and COST line parameters, the IS/OS line had higher correlations with the BCVA by multivariate analysis. No significant difference was observed in central retinal thickness between eyes with intact and nonintact COST lines. Eight (30.8%) of 26 eyes with BCVA >= 20/20 had nonintact COST lines at 12 months after the ERM surgery. Conclusions: Eyes with an intact COST line had better BCVA after ERM surgery. However, even at 12 months after ERM surgery, COST lines remained disrupted in many eyes with good BCVA.