To evaluate the ganglion cell-inner plexiform layer (GCIPL) thickness after internal limiting membrane (ILM) peeling with or without intravitreal gas injection (IVGI) or surgical induction of posterior vitreous detachment (PVD).

Eighty patients who were diagnosed with epiretinal membrane (ERM) or macular hole and who received surgical intervention were retrospectively reviewed. Forty patients were treated with ILM peeling and forty patients were treated with ERM removal, but not with ILM peeling. The patients were categorized according to ILM peeling, IVGI, and surgical induction of PVD. The GCIPL thickness was measured using optical coherence tomography, and the average and sectorial thickness of GCIPL were compared.

The GCIPL thickness in the ILM peeling group significantly decreased (-13.80 ± 22.63 µm; p < 0.001), but was not significantly different in the ERM removal without ILM peeling group, compared with the preoperative GCIPL thickness (+1.21 ± 22.53 µm; p = 0.546). The difference was statistically significant between the two groups ( p = 0.038). In the ILM peeling group, GCIPL thickness was not significantly different in the IVGI group (-17.41 ± 23.92 µm vs. -7.25 ± 19.05 µm; p = 0.109) and was significantly decreased in the surgical induction of the PVD group (-23.06 ± 23.92 µm vs. -7.25 ± 19.05 µm; p = 0.020). On sectorial analysis, reduction of the temporal GCIPL thickness was the largest and was significantly different compared with the nasal GCIPL thickness in ILM peeling group (-19.73 ± 28.55 µm vs. -7.42 ± 19.90 µm; p = 0.005).

ILM peeling and surgical induction of PVD may damage ganglion cells. Therefore, gentle ILM peeling and surgical induction of PVD may be needed to minimize ganglion cell damage, especially when ILM peeling is performed in glaucomatous patients.