Risk Factors for Neovascular Glaucoma after Vitrectomy in Patients with Proliferative Diabetic Retinopathy

ABSTRACT

PURPOSE: The use of pre- and intraoperative vitreous bevacizumab injection and combined lens extraction with vitrectomy in patients with proliferative diabetic retinopathy (PDR) is increasing. In this study we analyzed the incidence and risk factors of neovascular glaucoma (NVG) after vitrectomy for PDR. METHODS: Patients who underwent vitrectomy for PDR from January 2004 to June 2011 were retrospectively reviewed. The minimum follow-up was 12 months. The cumulative incidence of NVG was calculated using the Kaplan-Meier survival analysis. The patients were divided into 4 groups according to lens status (preoperative pseudophakic group, simultaneous cataract surgery group, sequential cataract surgery group, non-cataract surgery group). The differences in incidence between the groups were determined by the Chi-square test. Finally, to analyze the risk factors associated with the occurrence of NVG, the Cox's regression model was used. RESULTS: Of the 614 eyes (402 patients), 284 were males and 330 were females. The mean age was 55.8 +/- 10.46 years (range 30-81 years) and the mean follow-up period was 36.6 months (range 1-93 months). Thirty-four of 614 patients (5.5%) developed postoperative NVG after vitrectomy. The probability of NVG occurrence at 6 and 12 months after vitrectomy was 0.7% and 2.5%, respectively. The incidence between the 4 groups did not show a statistically significant difference. The risk factors for postoperative NVG were male gender (RR = 3.01 p = 0.004), preoperative intravitreal bevacizumab injection (RR = 7.20, p < 0.001), and reoperation (RR = 3.18, p = 0.0037). CONCLUSIONS: The frequency of NVG after vitrectomy in patients with PDR was 5.5%. Lens status was not associated with NVG occurrence. The risk factors related to NVG were male gender, preoperative intravitreal bevacizumab injection, and reoperation.