The relationship of retrobulbar hematomas to vision in cynomolgus monkeys

An experimental model has been developed to measure the effect of retrobulbar hematomas on functional vision in cynomolgus monkeys. In this model, functional vision was quantitated using flashed evoked visual potentials in five monkeys following creation of retrobulbar hematomas. In one monkey used as a control, functional vision remained impaired for 180 minutes following induction of retinal ischemia by increased intraorbital pressure. In two monkeys in which increased intraorbital pressure was relieved by anterior chamber paracentesis following 15 minutes of retinal ischemia, flashed evoked visual potential promptly returned to baseline level. In two additional monkeys in which increased intraorbital pressure was relieved following 30 minutes of retinal ischemia, flashed evoked visual potentials improved but never returned to baseline levels. This study demonstrates the usefulness of flashed evoked visual potentials in measuring functional vision in cynomolgus monkeys. This experimental model should prove useful in evaluating the effects of increased intraorbital pressure on functional vision and the effect of intervention on impaired vision due to retrobulbar hematomas. Further studies with larger numbers of animals are needed to clarify these preliminary studies and document longer-term effects of retinal ischemia secondary to retrobulbar hematomas.