Topical acetazolamide and methazolamide delivered by contact lenses

Topical acetazolamide has been previously found to be ineffective in lowering intraocular pressure (IOP). Using high-water-content soft contact lenses (Sauflon PW) soaked in acetazolamide, we observed a statistically significant ipsilateral decrease in IOP of 6.3 +/- 0.4 mm Hg in the treated eyes of albino rabbits. The duration of the effect was up to 7 1/2 hours. Methazolamide-soaked contact lenses produced a maximum unilateral reduction of similar magnitude but shorter duration. Both serum and aqueous humor analyses for pH, carbon dioxide pressure, bicarbonate, and base excess indicate that acetazolamide delivered by soft contact lenses is able to penetrate the cornea in sufficient concentration to lower IOP by a local mechanism in rabbits without significant systemic absorption.