The predictive value of ectopic inner retinal layer staging scheme for idiopathic epiretinal membrane: surgical results at 12 months.

Background/objectives: To assess the effect of ectopic inner foveal layers (EIFL) based staging scheme, foveal avascular zone (FAZ) alterations and other microstructural optical coherence tomography (OCT) findings on visual function for patients undergoing idiopathic epiretinal membrane (iERM) surgery.

Subjects/methods: In this retrospective study, patients who underwent 27 G pars plana vitrectomy (PPV) for idiopathic ERM with a minimum follow-up of 12 months were included. Preoperative and postoperative OCT scans, FAZ area measurements on en face OCT angiography images and mean retinal sensitivity (MRS) using microperimetry were recorded in all cases. The correlation of FAZ area, EIFL and other OCT parameters with preoperative and postoperative best-corrected visual acuity (BCVA) was analysed.

Results: In all, 112 eyes of 112 patients were included. Visual acuity improvement was statistically significant in all four stages; however, differences between Stages 2, 3 and 4 ERMs remained significant (p < 0.05). The presence and thickness of the EIFL was associated with worse baseline (p = 0.013; p = 0.005, respectively) and final (p < 0.001 for both) BCVA. The presence of cystoid macular oedema was associated with worse BCVA at baseline (p = 0.027) and postoperative month-6 (p = 0.04). The mean FAZ area was significantly reduced in all stages of ERM compared with the fellow eyes (p < 0.05 for all). Postoperative retinal sensitivity improvement was statistically significant in Stage 1 and Stage 2.

Conclusion: The presence of EIFL is an independent predictor of worse postoperative BCVA. Accordingly, despite significant BCVA improvements in all stages of ERM, visual acuity gain remains limited in eyes with Stage 3 and Stage 4 ERM.