BETAMETHASONE-INDUCED OCULAR HYPERTENSION IN RABBITS

The effect of subconjunctivally injected betamethasone on intraocular pressure (IOP) was studied in 85 albino New Zealand rabbits. IOP was m easured with a Mentor Model 30 classic pneumatonograph that was manome trically calibrated to the rabbit eye. Ocular hypertension was induced by weekly subconjunctival injections of a betamethasone suspension in to the left eye. In one experiment, 70 rabbits were given betamethason e for 4 weeks, while a second group of 10 rabbits received betamethaso ne for 11 weeks. The short-term effects of subconjunctival injections of betamethasone on IOP were also recorded in a third group of 5 rabbi ts. Weekly injections over 4 weeks resulted in an increase in IOP in t he treated eye, which was prolonged to 11 weeks by repeated weekly inj ections. A sustained increase in IOP was observed in the treated eye f or a period of 7 weeks. During the early hours after betamethasone inj ection, a transient decrease in IOP was registered in both eyes. The r esults show that weekly subconjunctival injections of betamethasone ca use a predictable increase in IOP in the treated eye which may be suit able for testing the short- and long-term effects of antiglaucoma drug s. Evidence suggesting that endogenous glucocorticoids may play a role in the development of ocular hypertension in human strengths the pote ntial value of this glaucoma model.