Vitreous cylinders.

Vitreous cylinders, a rarely discussed ophthalmologic entity, were studied in two clinical cases and in five enucleated eyes. The cylinders were found in four cases of ocular toxoplasmosis, one case of vitreous hemorrhage complicating a malignant melanoma, and one case of pars planitis and one of uveitis, both of unknown causes. Results of scanning electron microscopy in one specimen suggested that cylinders are formed by condensation of vitreous collagen fibers. We emphasize the nonspecific nature of this interesting vitreous finding.