Ganglion Cell-Inner Plexiform Layer Thickness after Epiretinal Membrane Surgery: A Spectral-Domain Optical Coherence Tomography Study

Abstract

To investigate postoperative macular ganglion cell-inner plexiform layer (GCIPL) thickness, determine the factors related to GCIPL thickness, and evaluate the association of GCIPL thickness with postoperative visual outcomes in patients with idiopathic epiretinal membrane (ERM). Retrospective, cohort study. Sixty-two patients with unilateral idiopathic ERM who were followed for ≥ 6 months after surgery. Ophthalmologic evaluations included best-corrected visual acuity (BCVA) assessment, spectral-domain optical coherence tomography, and macular visual field (VF) mean sensitivity (MS) as measured by Humphrey VF test. Macular GCIPL thickness in eyes with ERM was compared with that of the normal contralateral eyes 6 months after surgery. The correlation between the interocular difference in GCIPL thickness and postoperative visual outcome was evaluated. Postoperative macular GCIPL thickness, factors related to the interocular differences in GCIPL thickness, and correlations of GCIPL thickness with BCVA and macular VF MS 6 months after surgery. Macular GCIPL thickness was significantly lower in eyes with ERM 6 months after surgery (71.77 ± 10.21 μm) than in the unaffected contralateral eyes (81.69 ± 5.33 μm; P<0.001). Thirty-three subjects were followed for 1 year after surgery, and the macular GCIPL thickness in eyes with ERM did not significantly change between 6 and 12 months after surgery (71.77 ± 10.21 vs 70.64 ± 9.57 μm; P = 0.179). Preoperative central foveal thickness was the only factor significantly correlated with interocular differences in macular GCIPL thickness (r = 0.3677; P = 0.0033). Among patients with intact photoreceptor layers, a greater decrease in GCIPL thickness was correlated with a worse postoperative BCVA (r = 0.5209; P<0.0001) and a greater decrease in macular VF MS (r = -0.2845; P = 0.0390). Macular GCIPL thickness decreased after vitrectomy to remove an idiopathic ERM. The decrease in GCIPL thickness was significantly correlated with postoperative visual outcomes in patients with intact photoreceptor layers.