Frequency and risk factors for neovascular glaucoma after vitrectomy in eyes with proliferative diabetic retinopathy.

Purpose: To investigate the rate and risk factors for neovascular glaucoma (NVG) after vitrectomy in proliferative diabetic retinopathy (PDR).

Methods: Five hundred and twelve patients (512 eyes) with PDR who underwent vitrectomy between January 1, 2003 and June 30, 2009 at Kumamoto University Hospital, Japan, were retrospectively evaluated. Postoperative NVG was defined as neovascularization in the anterior segment and intraocular pressure (IOP) ≥ 22 mm Hg after vitrectomy. Kaplan-Meier survival analysis was applied to calculate the rate of NVG after vitrectomy. Risk factors for NVG after vitrectomy were identified by multivariable analysis using the Cox proportional hazards model.

Results: The mean follow-up period was 422 days. Twenty-seven of 512 patients (5.3%) developed postoperative NVG after vitrectomy. The probability of NVG occurrence at 6 and 12 months after vitrectomy was 6.0% and 7.1%, respectively. Male sex [relative risk (RR)=4.247; P=0.0032), younger age (RR=0.956/y; P=0.0237), higher baseline IOP (RR=1.203/mm Hg; P=0.0335), preoperative neovascularization in the anterior chamber angle (RR=8.899; P<0.0001), and presence of NVG in the fellow eye (RR=5.355; P=0.0013) were significant risk factors for postoperative NVG.

Conclusions: The frequency of NVG in PDR eyes within 1 year after vitrectomy was estimated as 7.1%. The risk is independently associated with male sex, younger age, higher baseline IOP, preoperative neovascularization in the angle, and NVG in the fellow eye.