Ocular effects of beta-adrenergic agents. XII Jules Stein Lecture.

The ocular effects of beta-adrenergic agonists and antagonists are reviewed. The permeability of the rabbit corneal epithelium was estimated for various instilled drugs, and difference in pharmacokinetics of timolol between the albino and pigmented rabbit demonstrated. The effects of the drugs on the cornea and the lens epithelium, and also the distribution of the adrenergic receptors in the intraocular muscles were discussed. The beta-adrenergic receptors are present in the ciliary processes of the rabbit as shown through studies by biochemical pharmacology and cytochemical electron microscopy. Adrenergic effects on the blood flow and the vascular permeability of the anterior uvea were discussed. The effects of adrenergic drugs on aqueous humor dynamics differ considerably among rabbits, monkey and the human subjects, and they were discussed separately for these species. The mechanism underlying the hypotensive effects of beta-adrenergic drugs is complex, but the available data indicate that in the human eye the hypotensive effects of epinephrine are attributed mainly to a decrease in the outflow resistance and the effects of timolol are principally to a reduction of aqueous humor formation.