[The ocular hypotonic effect induced by an angiotensin-converting enzyme inhibitor (captopril)]

The investigation aims at analysing in healthy and glaucoma subjects the effects of an angiotensin conversion enzyme inhibitor (Captopril) on intraocular pressure, local tolerance, influence on systemic circulation and to ascertain (or suggest) the mechanisms inducing this pressure lowering. The study is prospective, masked, in acute test (10 days) and includes a series of 14 healthy subjects and 18 patients with open angle primitive glaucoma. Following numerous experimental and clinical tests, Captopril isotonic solution 2.5% administered in ocular instillation 4 times/day proved to be the most appropriate.

Captopril solution 2.5% lowers intraocular pressure both in the normal subjects (average relief of 6.5 mm Hg) and in the glaucoma patients (8.9 mm Hg); hypotonic effects lasts for 6-8 hours; local tolerance is good; has no influence on systemic arterial pressure; tonography with constant Pt shows a 12% increase of C (insufficient to explain such a relief in intraocular pressure). The hypotesis that pressure lowering occurs (partially) by the stimulation of prostaglandin activity and consequently by improved uveoscleral drainage is suggested.

Captopril solution 2.5% administered topically lowers intraocular pressure without adversely influencing systemic and local circulation; local tolerance is good; the mechanisms of ocular hypotonizing effect are unknown.