Value of preoperative optical coherence tomography for predicting visual outcome after epiretinal membrane surgery

We assessed the value of preoperative optical coherence tomography (OCT) for predicting the visual outcome for patients undergoing macular surgery for epiretinal membranes (ERMs). In a retrospective trial, we analyzed the medical charts of patients who had received surgery for ERMs between January and August 2011. The best-corrected pre- and postoperative logMAR visual acuity was assessed. We pre- and postoperatively measured the central foveal thickness with high-resolution spectral-domain OCT and analyzed the structure of the outer retinal layers (retinal pigment epithelium, photoreceptors, and external limiting membrane) before and after surgery. The study included 49 patients (23 male, 27 female) with an average age of 69 years (SD 6.7) who had received macular surgery during the above-mentioned period. For phakic eyes (n = 34), treatment had also included phacoemulsification and intraocular lens implantation. Postoperative follow-up examinations and OCT controls had been conducted after an average of 9 weeks (SD 5). The mean improvement in visual acuity was 2.4 lines (SD 2.3; p < 0.001). For patients with phakic eyes, the combination of vitrectomy and cataract surgery resulted in a slightly better, but insignificant increase in visual acuity than for patients with primary pseudophakia (Δ = 0.05, p = 0.46). On average, central foveal thickness regressed by 94 μm (SD 129 μm). Linear regression showed a significant linear relationship between the reduction of central foveal thickness and improvement of visual acuity (R (2) = 0.16, B = 0.71, p = 0.004). A decrease in foveal thickness by 100 μm resulted in an increase in visual acuity by 0.71 lines. Visual improvement did not significantly differ between the group of patients with intact outer retinal layers before surgery and the group of patients with preoperative defects of the retina (p = 0.085). We found a significant linear relationship between the reduction of central foveal thickness and improvement of visual acuity for patients undergoing surgery for ERM. However, the preoperative OCT status (intact vs. broken) of the outer retinal layers did not correlate with the change in visual acuity.