Sixty-four consecutive pars plana vitrectomies were performed with the Douvas roto-extractor for anterior and posterior vitreous opacities. Eighty-four per cent of the anterior segment vitrectomy patients obtained improvement in visual acuity after surgery. Only 60% of the posterior segment patients obtained improvement in visual acuity, while only 45% of the eyes with active proliferative diabetic retinopathy had improved vision.