Patientswho 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 cataractsurgery group, sequential cataractsurgery group, non-cataractsurgery 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 malegender (RR = 3.01 p = 0.004), preoperative intravitreal bevacizumabinjection (RR = 7.20, p < 0.001), and reoperation (RR = 3.18, p = 0.0037).