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Does Preoperative Epiretinal Membrane OCT staging Predict Postoperative Visual Prognosis ?

The purpose of this study was to assess the association between preoperative epiretinal membrane (ERM) staging and postoperative visual acuity in phakic and pseudophakic patients.

Patients operated for unilateral ERM between 2014 and 2021 at the CUO-CHU de Québec – Université Laval were retrospectively reviewed. Preoperative ERM were graded based on the optical coherence tomography staging proposed by Govetto et al. (2017). Main outcomes were best-corrected visual acuity (BCVA) at 3 months and final follow-up in logarithm of the minimal angle of resolution (logMAR). These were compared between ERM grades using Kruskal-Wallis tests. A generalized linear model was produced for final BCVA, correcting for confounding factors, including age, preoperative BCVA and ERM grade, lens status, tamponade used, and total follow-up.

Of the 184 patients, 51% (n=93) were female and 49% (n=91) were male. Mean age at presentation was 70&plusmn;9 years. Our cohort were mostly phakic preoperatively (n=127, 69%). Most patients (n=130, 71%) also had concurrent internal limiting membrane (ILM) peel. Air was the most common tamponade used (n=113, 61%), followed by SF6 gas (n=62, 33%). ERMs were mostly associated with posterior vitreous detachment (PVD) in 67 (36%) cases, previous cataract surgery in 53 (29%), and previous or active retinal detachment (RD) in 44 (24%). Preoperatively, there were 26 (14%) stage 1 ERMs, 59 (32%) stage 2, 74 (40%) stage 3, and 20 (11%) stage 4. Significant differences were observed between ERM grades in 3-month BCVA (median [Q1, Q3] BCVA in stage 1: 0.30 [0.14, 0.40], stage 2: 0.34 [0.19, 0.44], stage 3: 0.33 [0.18, 0.44], stage 4: 0.59 [0.48, 0.90]; p=0.002) and final BCVA (median [Q1, Q3] BCVA in stage 1: 0.20 [0.08, 0.37], stage 2: 0.22 [0.06, 0.44], stage 3: 0.24 [0.12, 0.39], stage 4: 0.46 [0.22, 0.83]; p=0.05). The generalized linear model also showed that lower preoperative ERM stages was a good predicter of better final BCVA relative to stage 4 ERM (B [95% confidence interval] for stage 1: -0.32 [-0.63, -0.01], p=0.04; stage 2: -0.40 [-0.67, -0.13], p=0.004; stage 3: -0.47 [-0.73, -0.21], p<0.001) after adjusting for confounding factors (including preoperative visual acuity).

The present study has shown an association between preoperative ERM stage and postoperative visual acuity. Stages 3 and 4 are distinguished from stage 1 and 2 by the presence of ectopic inner foveal layers. Previous studies have suggested that ectopic inner foveal layers may persist even after surgical ERM peel1 and might explain poorer final BCVA for advanced stages. Moreover, prior literature also proposed that chronic dislodgment of retinal layers, found in stage 4 ERM, might contribute to photoreceptor&rsquo;s damage1 and aligns with our finds. OCT staging system proposed by Govetto and al. (2017) is an interesting additional clinical tool for ERM management. 

In this cohort of patients operated for primary and secondary ERMs, 3-month BCVA and final BCVA significantly differed by ERM grades, particulary with stage 4 ERM. Preoperative ERM staging seems to be an important predicter of the visual potential.