Pars plana vitrectomy and internal limiting membrane peeling in epimacular membranes: correlation of function and morphology across the macula.

PURPOSE To analyze the correlation between morphological and functional results 12 months after epiretinal membrane (ERM) surgery. METHODS 31 eyes from 31 consecutive patients with metamorphopsia and best corrected visual acuity (BCVA) below 20/32 underwent a transconjunctival 23- gauge vitrectomy with ERM and internal limiting membrane peeling. Preoperatively and 3, 6 and 12 months postoperatively, we assessed BCVA, microperimetry (MP-1) and spectral domain optical coherence tomography (SD-OCT). Photoreceptor inner and outer segment (IS/OS) was graded on SD-OCT images and correlated with microperimetry measurements in the fovea and parafoveal region. RESULTS The postoperative BCVA was significantly better in eyes with an intact IS/OS junction (p < 0.01). In addition, the mean defect depth was postoperatively decreased in the foveal and parafoveal area in eyes with an intact IS/OS junction. A correlation of SD-OCT IS/OS images and microperimetry in eyes with improvement in BCVA of at least 2 lines revealed a statistically significant result for the parafoveal quadrants (p < 0.011 for SD-OCT and p < 0.005 for microperimetry) but not for the foveal area alone. CONCLUSIONS The IS/OS regeneration in the parafoveal quadrants contributes significantly to the recovery of BCVA following ERM surgery. Consequently, functional and morphological tests of the macular area should not be limited to the fovea but should be extended to the parafoveal region.