Risk of newly developing visual field defect and neurodegeneration after pars plana vitrectomy for idiopathic epiretinal membrane

Background/Aims Pars plana vitrectomy (PPV) is widely performed in patients with idiopathic epiretinal membrane (iERM) to improve vision. Postoperative visual field defects (VFDs) have been previously reported. However, whether they occur when using the most recent PPV system, and the frequency of VFDs as measured by standard automated perimetry, remain poorly documented and were examined in this study. Methods Data of 30 eyes (30 patients; mean age, 66.1 years; 15 men) who underwent PPV for iERM during February 2016-June 2019 and had preoperative and postoperative visual field measurements using standard automated perimetry (Humphrey visual field analyser 30-2 program) were retrospectively analysed. Eyes with diseases other than iERM, including moderate-to-severe cataract or preoperative VFDs were excluded. Results VFD, defined by the Anderson and Patella's criteria, was found in 73.3% of the eyes 1 month after PPV. After age adjustment, internal limiting membrane (ILM) peeling was identified as a risk factor for postoperative VFD (p=0.035; 95% CI 1.173 to 92.8). Postoperative VFD was frequently observed nasally (86.4%, p=0.002), and on optical coherence tomography measurements, ganglion cell layer (GCL) thinning was found temporal to the fovea (p=0.008). Thinning of the superior and inferior retinal nerve fibre layers and of the GCL temporal to the fovea were significant in eyes after ILM peeling (all p<0.05). Conclusion ILM peeling may cause inner retinal degeneration and lead to the development of VFDs after PPV, which should be further examined.