Risk factors for neovascular glaucoma after vitrectomy in eyes with proliferative diabetic retinopathy

Purpose: To investigate the potential risk factors for neovascular glaucoma (NVG) after vitrectomy in eyes with proliferative diabetic retinopathy. Subjects and methods: In this retrospective, observational, comparative study, patients with proliferative diabetic retinopathy who underwent vitrectomy at Toho University Sakura Medical Center between December 2011 and November 2016 and who were followed for ≥12 months after surgery were included. Subject parameters examined included age, glycated hemoglobin (HbA1c), fasting blood glucose, administration of insulin, and estimated glomerular filtration rate. Ocular parameters examined included preoperative best-corrected visual acuity, preoperative IOP, operative history (specifically panretinal photocoagulation), lens status, ocular pathology (eg, iris/angle neovascularization, tractional retinal detachment, diabetic macular edema, vitreous hemorrhage, combined tractional retinal detachment), intraoperative retinal tamponade use, vitrectomy gauge, combined lens extraction/vitrectomy procedure, subsequent surgical procedures, and pre- and postoperative intravitreal bevacizumab. Correlations between variables and postoperative NVG development were examined using logistic regression analyses (backward elimination method). Results: A total of 254 eyes of 196 consecutive subjects (146 men [74.5%], 54.0±10.8 years old) were included. Sixty of 254 eyes (23.6%) developed NVG. Several preoperative factors increased the risk of developing NVG, including iris/angle neovascularization (P=0.042), preoperative high IOP (P=0.005), low HbA1c (P=0.004), and administration of insulin (P=0.045). Intraoperative retinal tamponade also increased NVG risk (P=0.021, backward elimination method). Conclusion: Preoperative parameters such as elevated IOP, iris/angle neovascularization, fasting blood sugar and HbA1c discrepancies, administration of insulin, as well as use of retinal tamponade during retinal surgery were identified as the risk factors for developing NVG.