The effects of various levels of intraocular pressure on the rabbit's outflow system

The effects of various levels of intraocular pressure on the morphology of the rabbit outflow system were investigated. In a total of 20 rabbits, intraocular pressure was maintained at various levels between 0-50 mmHg in the experimental eye and at 20 mmHg in the control eye for 1 hr. Flow rates into the eyes were measured by following the movement of a miniscus through a calibrated capillary tube. Progressive increase in pressure lead to distension and enlargement of the ciliary cleft. The meshwork tissues stretched and distended, and the vessels of the angular aqueous plexus had pressure-sensitive giant vacuoles of their endothelium. These vessels were prone to closure at pressures of 30 mmHg and greater. Difficulties associated with quantitation of giant vacuoles in this species were discussed.