The effect of lensectomy on the incidence of iris neovascularization and neovascular glaucoma after vitrectomy for diabetic retinopathy.

We analyzed a consecutive series of 596 eyes that underwent vitrectomy for complications of diabetic retinopathy to determine the postoperative incidence of iris neovascularization and neovascular glaucoma. Survival curves for various factors were plotted, showing the cumulative incidence of these complications at various postoperative times up to one year. Eyes in which the lens was removed during vitrectomy had a statistically significant (P less than .001 by log-rank test) increase in the postoperative incidence of both iris neovascularization and neovascular glaucoma compared to eyes in which the lens was not removed. Lens removal at vitrectomy increased the risk of postoperative iris neovascularization by a factor of more than three and the risk of neovascular glaucoma by a factor of more than four. Other factors associated with a significantly increased incidence of postoperative iris neovascularization were severe preoperative retinal neovascularization and the absence of preoperative scatter retinal photocoagulation. Neither of these two factors nor postoperative retinal detachment invalidated or reduced the effect of lensectomy on increased postoperative iris neovascularization when all factors were considered simultaneously. This study showed a statistically significant increase in the postoperative incidence of neovascular glaucoma in eyes undergoing combined lensectomy and vitrectomy compared to eyes in which the lens was not removed.