The factors affecting morphological and functional changing in retina after epiretinal membrane peeling

The aim: To evaluate the factors that affects the changing of function and morphology of the retina after surgical treatment in patients with epiretinal membrane (ERM). Materials and methods: 52 eyes of 51 patients diagnosed diagnosed ERM were performed, ERM peeling and follow-up for 12 months between August 2015 and August 2016 were enrolled to the study. Complete ophthalmologic examination of were performed preoperatively and at 1st month, 3rd months, 6th months, and 12th months postoperatively and optical coherence tomography (OCT) images were devaluated. Results: Of the patiens, 30 (58.8%) were female and 21 (41.2%) were male. There were no any significant difference in the parameters evaluated preoperatively and 12th months postoperatively in terms of gender (p>0.005). The mean age was 66.9±8.2 years. The mean baseline best corrected visual acuity (BCVA) in the patients who were under 67 ages and over 67 ages was 0.736±0.49 logMAR and 0.874±0.36 logMAR respectively and the difference between them was statistically significant (p=0.042). No any significant difference was found in the other parameters (p>0.005). Of the eyes, 25 (48.1 %) have idiopathic ERM and 27 (51.9 %) have seconder ERM. Parafoveal temporal outer retina thickness was 139.44±29.31 µm in the idiopathic group in baseline, whereas, it was 165.81±45.41 µm in the seconder ERM group and the difference between them was significant statistically (p=0.020). Only the change of thickness in the parafoveal temporal outer layer was significant between preoperative and postoperative the measurement (p=0.009), accompaining an increase in the idiopathic group and a decrease in the seconder group. When the epiretinal membrane was divided into two subgroups (focal and diffüz adherent), according to the OCT findings, only the change in parafoveal temporal thickness was significantly higher in the focal adherent ERM group (p=0.028). The mean visual acuity of the subjects was 0.81±0.4 logMAR at baseline and 0.54±0.4 logMAR at 12th months postoperatively (p<0.001). There was a significant positive correlation between BCVA's obtained preoperatively and at 12th month postoperatively (r=0.573, p=0.001). While there was no any correlation between at baseline and postoperative 12th month in term of CRT and BCVA (r=0.07, p=0.563; r=-0.14, p=0.282), there was significant correlation between the change in CRT and the change in BCVA (r=0.395, p=0.003). Despite a significant decrease in the CRT and parafoveal nasal and iner layers of temporal retina thicknesses (p<0.001, p<0.001, p<0.001 respectively), there were no any significant change in the parafoveal nasal and outer layers of temporal retina after ERM surgery (p=0.877, p=0.230 respectively). In the comparison of patients who had intact IS/OS line and not, while there was no any significant difference between two subgroups in BCVA preoperatively, there was a significant increase at 12th month postoperatively in the intact IS/OS line group (p=0.057, p=0.001 respectively). Conclusion: After surgical peeling of ERM, functional and morphologic improvement is achieved in the retina. The baseline visual acuity and the integrity of IS/OS line are important prognostic factors for postoperative visual acuity.