SUMMARY The histological findings of the wound, the vitreous, and the retina in the rabbit eye with experimental posterior penetrating injury are described. Wound healing had just begun at 3 days after injury and was well established by 9 to 12 days. It involved proliferation of cells from the episclera and from the choroid. The progression to a fibrous ingrowth from the wound occurred only in eyes with blood in the vitreous. The intravitreal fibroblastic proliferation had begun at 6 days after injury and seemed to be derived from the choroid, the nonpigmented ciliary epithelium and, posteriorly, from the optic nervehead. During the development of retinal detachment the configuration of the peripheral and posterior retina, together with the orientation of vitreous strands, suggested the presence of vitreous traction. We postulate that the presence of contractile fibroblasts (myofibroblasts) in the vitreous may provide the mechanism for vitreous traction. The retinal detachments were also characterised by epiretinal and subretinal membranes, but these were not prominent. The end-stage appearance of a soft, shrunken eye with cyclitic membrane formation and retinal detachment resembles the outcome in many human eyes after severe penetrating injuries.Severe penetrating injuries in human eyes are characterised histologically by intraocular fibrosis with cyclitic membrane formation and traction retinal detachment (Hogan and Zimmerman, 1962;Coles and Haik, 1972). In fact, traction retinal detachment is the main reason for loss of vision in those injuries which are confined to the posterior segment (Eagling, 1975).It has been shown in the preceding paper (Cleary and Ryan, 1979) that the experimental model of a posterior penetrating injury in the rabbit eye results in cyclitic membrane formation and in traction retinal detachment. In the present paper we describe the sequence of histological changes.
Materials and methodsAs previously described, rabbit eyes were injured by a standard wound which was 8 mm long through the pars plana, avoiding the lens and the peripheral retina. Prolapsed vitreous was abscissed and the wound carefully closed by microsurgical techniques with interrupted sutures of 8-0 silk. After wound Address for reprints: Mr Philip E. Cleary, FRCS, Ardkeen Hospital, Waterford, Ireland closure the fundus was inspected by indirect ophthalmoscopy and the area of the wound and the peripheral retina examined by scleral indentation. In some eyes autologus blood and in others balanced salt solution was injected through a 25-gauge needle inserted through the wound and under ophthalmoscopic control into the mid-vitreous, with avoidance of the lens and the retina.The eyes were enucleated at 3-day intervals for the first 3 weeks after injury as well as at 2 and 3 months after injury. Each group consisted of a minimum of 3 eyes. The eyes were fixed in Bouin's fixative for 24 hours and were then sectioned through the optic nerve and midpoint of the wound for gross examination. Each half eye was examined under the diss...