Pars plana vitrectomy in patients with severe renal and retinal affections was considered a relative contraindication for operation. Despite relative failure (deterioration of visual acuity) it is possible in these patients, and in half of them it improved their quality of life. The risk of peroperative and postoperative damage can be reduced by suitable selection of anticoagulants. The favourable effect of tamponade with silicon oil on the postoperative course must be tested in a con- trolled trial.

        Key words: posterior vitrectomy, haemodialysis, proliferative diabetic retinopat- hy