PurposeTo investigate the potential risk factors for neovascular glaucoma (NVG) after vitrectomy in eyes with proliferative diabetic retinopathy.Subjects and methodsIn 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).ResultsA 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).ConclusionPreoperative 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.

This study suggests that epinephrine, used in combination with intravitreal infusion solution, may decrease ONH blood flow during vitreous surgeries, as indicated by measurements obtained via a modified LSFG technique. Attention must be paid to the effects of intravitreal infusion of epinephrine on ocular circulation, particularly ONH blood flow.

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Our results suggest that HTN and HL impair autoregulation in the vascular component of ONH blood flow during vitrectomy.

The ONH blood flow in subjects without systemic disorders was initially lower, but began to recover 5-10 minutes after a 15 mmHg elevation in IOP. These results indicate that autoregulatory mechanisms of ONH blood flow may help to minimize the effects of IOP elevations and fluctuations during vitreous surgery.