Pharmacological validation of a feline model of steroid-induced ocular hypertension

Objective: To validate pharmacologically the feline model of steroid-induce d ocular hypertension. Methods: Serial studies were conducted in domesticated adult female cats tr ained to accept topical ocular drug administration and pneumotonometry. To establish intraocular pressure (IOP) values for each study, measurements we re performed at the same time of day for 6 consecutive days. Beginning on d ay 7, cats received either steroid or vehicle administered topically to bot h eyes three times a day for approximately 28 days. The IOP measurements we re performed daily. Results: After 5 to 7 days of treatment with 0.1% dexamethasone or 1.0% pre dnisolone acetate, IOP began to increase, reaching peak values within 2 wee ks. These values were sustained throughout dosing but declined rapidly to b aseline upon cessation of treatment. Maximum IOPs for the dexamethasone- an d prednisolone-treated groups averaged 4.5 +/- 0.3 mm Hg (n = 12) greater t han the mean IOP value obtained in vehicle-treated cats. Cats treated with 0.25% fluorometholone, 1.0% loteprednol etabonate, and 1.0% rimexolone exhi bited increases of 0.6, 1.2, and 1.7 mm Hg, respectively. These values were significantly lower than those observed following treatment with dexametha sone or prednisolone. Conclusions: The ocular hypertensive effects of selected anti-inflammatory topical ocular steroids in this model are consistent with clinical findings . Clinical Relevance: This feline model is a useful tool for assessing the po tential IOP liability of novel antiinflammatory steroids.