We have recently developed a technique for constant pressure perfusion of the aqueous outflow pathway of the eye. Our preliminary studies, conducted in the calf eye, show surprisingly that the manipulations necessary for preparing the outflow pathways and attached corneoscleral shell for perfusion do not greatly disrupt normal aqueous outflow physiology and anatomy according to the following criteria: 1. facility of outflow is similar before and during outflow pathway perfusion 2. as in the intact eye, facility of outflow decreases with increased IOP 3. removal of outflow resistance tissue greatly increases facility of outflow 4. morphology of outflow tissues remains normal Use of the perfused outflow pathway model may enable the creation of valuable in vitro preparations which may provide much needed information about the pathogenesis of primary open-angle glaucoma.