We performed pars plana vitrectomy in 15 patients with physical changes and visual loss believed to indicate impending macular hole formation. Twelve (80%) of 15 eyes have not progressed to macular holes during a minimum follow-up period of 15 months (average, 26 months). In these 12 patients final vision was within one line of the preoperative vision in four eyes, improved two or more lines in five eyes, and was two lines worse in three eyes. Decreased vision in all three eyes was the result of progressive lenticular nuclear sclerosis. A thin sheet of cortical vitreous fibers was sometimes found intraoperatively on the surface of the retina, despite an apparent complete posterior vitreous detachment.