Traumatic posterior vitreous detachment was studied in a monkey model of posterior penetrating eye injury with retinal laceration and intravitreal blood. Posterior vitreous detachment can occur as a separation at the level of the internal limiting membrane, or as a cleavage within the vitreous. The foot processes of Mueller cells were found to be altered in eyes with detached vitreous. Epiretinal membranes were seen to proliferate through cracks in the internal limiting membrane. The internal limiting membrane beneath the epiretinal membrane appeared to be wrinkled, suggesting a contractile property of the epiretinal membrane. The plane of separation in posterior vitreous detachment may be of fundamental importance in the formation of epiretinal membranes and subsequent development of retinal detachment.