[Intraoperative risk factors associated with visual acuity outcomes of pars plana vitrectomy in idiopathic epiretinal membrane].

Objective: To evaluate intraoperative risk factors related to the postoperative visual acuity in idiopathic epiretinal membrane (IERM) . Methods: According to the well-established study criterion, a retrospective observational study was carried out on 37 eyes of 37 patients with epiretinal membrane peeling surgery for IERM between January 2014 and January 2015. Intraoperative situations during membrane peeling were documented, including complexity of operation, superficial hemorrhage and the state of indocyanine green (ICG) staining. Best-corrected visual acuity (BCVA) measurement and optical coherence tomography were performed before and 1, 3, 6 and 12 months after surgery. Multifocal electroretinography and fundus fluorescein angiography were conducted at 6 months postoperatively. The patients were divided into two groups based on the BCVA (≥0.5 and<0.5) at 6 months after surgery. The BCVA was converted to logarithm of the minimum angle of resolution (logMAR) equivalents for statistical analysis. The relationship between intraoperative factors and postoperative visual acuity was analyzed by multiple logistic regression analysis. Results: All patients completed follow-ups in an average duration of (14.41±2.33) months. Among the 37 patients, 28 patients (75.7%) were in the BCVA ≥0.5 group. and 9 patients (24.3%) were in the BCVA<0.5 group. Statistical analysis revealed that superficial hemorrhage during membrane peeling was associated with poor visual acuity after surgery (OR: 7.221, 95% CI: 1.775-29.372, P=0.006) . The peeling complexity was positively increased with presence of superficial hemorrhage (γ=0.336, P=0.042) and ICG staining (γ=0.593, P=0.000) . The electroretinography revealed that the average latency of N1 wave at ring 1 in eyes with superficial hemorrhage (16.88±1.27)ms was longer than that in eyes without superficial hemorrhage (12.80±4.21)ms at 6 months postoperatively (t=-2.187, P= 0.042). The fluorescein angiography showed 8 in 10 eyes with superficial hemorrhage had leakage on the macular fovea. Conclusions: Superficial hemorrhage in IERM peeling is a risk factor for the poor postoperative visual function. Complex peeling contributes to superficial hemorrhage and the positive staining of ICG. (Chin J Ophthalmol, 2017, 53:344-351).