Paul Anton Cibis (1911-1965) was one of the pioneers of modern vitreoretinal surgery. He reasoned that the pathology of complex retinal detachments was intravitreal fibrosis and concluded that the optimum surgery was the injection of liquid silicone oil into the vitreous cavity to dissect fibrous membranes from the retinal surface and use the silicone for retinal tamponade. Prior to the invention of pars plana vitrectomy, such surgery was innovative, even daring. These surgical techniques were an important advance in directly operating on the vitreous in retinal detachment surgery. However, Cibis' contributions to vitreoretinal surgery only occupied the last 10 years of his tragically short life. Prior to his practice in retinal surgery, he made contributions to basic research in physiologic optics, local retinal adaptation, and the effect of ionizing radiation and atomic energy on the globe.