Choroidal Thickness Changes Following Vitrectomy in Epiretinal Membrane Based on the Optical Coherence Tomography Pattern

Purpose: To analyze the influence of morphological classification in epiretinal membrane (ERM) based on surgical outcomes and optical coherence tomography (OCT) of the postoperative choroidal thickness. Methods: This observational study included 122 eyes with ERM who underwent vitrectomy. Using OCT, the preoperative ERM was classified into six types: cystoid macular edema (CME), convex, flat, normal foveal contour (Normal), pseudolamellar hole (PLH), and vitreomacular traction (VMT). The preoperative multifocal electroretinogram (mfERG), postoperative change in sub-foveal choroidal thickness (SCT), central macular thickness (CMT), and best-corrected visual acuity (BCVA) were compared. Results: Preoperative sub-foveal choroidal thickness increased in the VMT type compared to the fellow eye (207 mu m vs. 234 mu m, p = 0.028). Choroidal thickness decreased in all types at 12 months after vitrectomy (all, p < 0.05). There was a positive linear correlation between the mfERG and the preoperative BCVA (p = 0.001). The initial visual acuity was best in the Normal type followed by the flat, PLH, convex, CME, and VMT types (p = 0.001). The final visual acuity was the best in the Normal type, followed by the PLH, Flat, VMT, Convex, and CME types (p = 0.030). Gas tamponade during the surgery did not affect the surgical outcomes of the CMT (p = 0.458), BCVA (p = 0.550), and SCT (p = 0.127). Conclusions: Preoperative SCT increased only in the VMT type, but choroidal thickness decreased in all types after vitrectomy, regardless of the preoperative morphology.