Separate, randomized, double-masked clinical studies were conducted to determine the therapeutic efficacy of fluorometholone acetate, a new ophthalmic corticosteroid formulation, in suppressing external ocular inflammation (conjunctivitis, episcleritis, scleritis). Fluorometholone acetate 0.1% was compared to fluorometholone 0.1%, and the acetate formulation was found to be significantly (p = 0.03) more effective. Fluorometholone acetate 0.1% also was compared to prednisolone acetate 1.0%; there was no significant difference (p = 0.49) between these two corticosteroids in their ability to suppress external ocular inflammation. It appears that alteration of fluorometholone from its alcohol base to its acetate derivative changes the drug from a moderately effective to a highly effective anti-inflammatory agent.