Gonioscopy, performed within 48 hours of traumatic hyphema, revealed not only angle recession but also a high incidence of damage to the trabecular meshwork and the Schlemm canal. These trabecular lesions tend to scar and become much more difficult to recognize over the ensuing weeks. Large tears into the ciliary body (angle recession) also had a tendency to "close." Using a specially calibrated BB gun hyphema was induced in rhesus monkeys. Trabecular tears were recognized by gonioscopic and histologic examination. Impaired outflow facility developed between 10 and 30 days after injury in the one surviving animal studied to date. In patients developing open-angle glaucoma years after trauma, evidence of past trabecular injury was seen by gonioscopy in addition to the obvious ciliary body tears (angle recession). The "normal" fellow eye had early glaucoma, ocular hypertension, or "high normal" intraocular pressure. The evidence presented supports the hypothesis that traumatic glaucoma is the result of trabecular meshwork injury from the original trauma and the rapid scarring that results, in combination with an underlying predisposition for the development of primary open-angle glaucoma and the passage of time.