Vitreous samples were obtained from 41 eyes undergoing vitrectomy, and radioimmunoassays were performed to measure concentrations of the prostaglandins PGE2, PGF2 alpha, prostacyclin, and thromboxane. Presumably physiological levels (approximately 100 picograms/ml) were found in vitreous from eyes undergoing cataract extraction. Eyes with vitreous haemorrhage, retinal detachment, or cystoid mac...