Introduction The effect of acetazolamide (Diamox), a carbonic anhydrase inhibitor, on the intraocular pressure of humans was first reported by Becker (1954), who pointed out the value of this drug in the treatment of glaucoma. Becker's observations have been confirmed and extended by other investigators (Grant and Trotter, 1954; Breiner and Gortz, 1954; Leopold, Eisenberg, and Yasuna, 1955). At the present time the value of acetazolamide in the short-term therapy of some types of glaucoma has been very well established. Considerable evidence has been accumulated to indicate that acetazolamide is also effective in controlling the intraocular pressure over a long period in eyes with chronic glaucoma previously inadequately controlled by topical medication (Becker, 1955; Kupfer, Lawrence, and Linner, 1955; Leopold and Carmichael, 1956, and others). Unfortunately, acetazolamide is not free of toxic effects. Undesirable side-reactions account for a great percentage of therapeutic failures when the drug is used on a