Medical therapy for experimental hypotony

J. E. Pederson and H. M. MacLellan

Experimental hypotony was induced in rhesus monkeys by the following procedures: ciliochoroidal detachment, retinal detachment, or cyclodialysis. Two days later, at the time of greatest hypotony, 10% methacholine chloride was deposited in the cornea by iontophoresis, and 0.25% physostigmine salicylate ointment was applied topically to each eye. The intraocular pressure rose to normal levels in all eyes for eight to 24 hours. The peak rise in IOP occurred one to four hours after drug administration and was 7.2, 6.8, and 11.3 mm Hg higher than the pretreatment levels in eyes with ciliochoroidal detachment, retinal detachment, and cyclodialysis, respectively. In a group of normal eyes, this drug combination caused a transient 5.7 mm Hg fall in IOP. The mechanism of pressure elevation by methacholine and physostigmine probably is caused by stimulation of aqueous humor formation or reduced uveoscleral outflow, or both.