Condensation and contraction of the vitreous have been implicated in the development of vitreoretinal traction and traction retinal detachment after penetrating ocular injury. In this study, using the inorganic dye ruthenium-red, we studied ultrastructural changes in vitreous in the rabbit eye after standard penetrating injury and intravitreal blood injection. In normal rabbit vitreous the collagen fibrils have a regular arrangement. In contrast, after a penetrating injury the collagen fibrils appear focally condensed. While it appears unlikely that such a network could alone produce tractional or directional forces, these alterations along the collagen fibrils could provide a scaffold along which contractile cells migrate into the vitreous.