beta-Blockers and the eye: an overview

Some beta-adrenoceptor blocking drugs are exciting new ocular hypotensive compounds. Unlike pilocarpine, the mainstay of glaucoma treatment for the last 100 years, beta-blocking agents do not contract the pupil nor interfere with vision even in patients with central lens opacities. They also do not cause spasm of the ciliary muscle producing transient myopia and disturbance of accommodation. Paradoxically, one of these agents, timolol, causes a fall in intraocular pressure when administered locally even in patients responding to beta-agonists with a reduction in intraocular pressure. Concomitant administration of timolol with epinephrine seems to enhance its ocular hypotensive effect in many patients. The exact mode of action of beta-blockers in reducing intraocular pressure is unknown but appears to primarily reduce aqueous production. This new class of drugs seems destined to play an important role in the treatment as well as in the understanding of glaucoma.