ObjectiveTo observe the changes of the structure and visual function of the retina in patients with or without the ectopic inner foveal layers (EIFL) and to explore the factors influencing the recovery of visual function in patients with idiopathic epimacular membrane (IMEM).MethodsA retrospective clinical study. From March 2015 to June 2019, 90 patients with MEM who were diagnosed by Ophthalmic Center of the Second Hospital of Hebei Medical University were enrolled in the study. All patients were examined by best corrected visual acuity (BCVA) and frequency domain optical coherence scan. BCVA was recorded by Snellen vision table, and it was converted into the minimum resolution angle logarithm (logMAR) vision. Among 90 eyes, IMEM grade 2-4 was 68 (75.6%, 68/90), 18 (20.0%, 18/90), 4 (4.4%, 4/90), respectively. According to this, the grade 2 was set as group A, and the grade 3 and grade 4 were combined to group B. There was no significant difference in age (t=0.015), sex composition ratio of patients between two groups (χ2=0.060) and the average of central macular thickness (CMT) (F=2.277) (P=0.904, 0.809, 0.141). The difference of average logMAR and BCVA was statistically significant (F=35.913, P=0.000). All patients underwent 25G pars plana three channel vitrectomy with simultaneous removal of epiretinal membrane and internal limiting membrane. BCVA, CMT and improvement of IMEM grading were observed at 1, 3, 6 and 12 months after operation. BCVA, EIFL thickness and CMT were compared before and after operation by single factor repeated variance analysis; Fisher exact probability method was used to compare the changes of the anatomical structure of the eyes in the two groups at 12 months after operation.Results1, 3, 6, 12 months after operation, the average eyes of logMAR BCVA in group A were 0.50±0.13, 0.38±0.12, 0.27±0.12, 0.19±0.10. The patients in group B were 0.66±0.14, 0.60±0.13, 0.54±0.14, 0.52±0.14. CMT in group A were 364.82±81.29, 281.65±72.45, 228.55±55.34, 182.84±56.13 μm. The patients in group B were 455.88±69.60, 440.18±68.65, 383.76±65.38, 371.39±66.60 μm. The difference was statistically significant in the two groups (BCVA: F=37.913, 11.479, 24.250, 39.013; P=0.000, 0.002, 0.000, 0.000. CMT: F=10.987, 39.610, 55.789, 79.987; P=0.002, 0.000, 0.000, 0.000). In group A, IMEM was improved to 57 eyes of grade 1 on 12 months after operation. Among the 18 eyes in group B, IMEM was improved to 1 and 3 eyes in level 1 and level 2, respectively, and no improvement was found in 4 eyes in grade 4. The difference was statistically significant (P=0.000) in the improvement of the number of eyes in the two groups.ConclusionsThe patients with IMEM without EIFL have better visual prognosis and reversible anatomical changes. EIFL is an important factor affecting the visual function and anatomical structure recovery after operation.