Pars plana virectomy. Preoperative evaluation

We have outlined the essential considerations in evaluating patients for closed vitrectomy and have attempted to show the importance of each. In general, we recommend closed virectomy under the following conditions: (1) vitreous opacities showing no resolution after six months of observation, (2) vision which is worse than 20/200 but has at least light perception with accurate projection, (3) there is no rubeosis iridis or glaucoma, (4) ultrasonography, ERG, and VER reveal a functional retina and optic nerve, and (5) the benefit outweighs the risk of surgery.