Morphological Changes in the Ciliary Epithelium by Instillation of Befunolol

ABSTRACT

The introduction of beta-adrenergic blocking agents for the treatment of glaucoma was a major advance in the continued search for medications that effectively control the intraocular pressure with minimal side effect. Beta-adrenergic blocking agents block the aqueous pump of the ciliary epithelium resulting in decreased aqueous formation and drop in intraocular pressure. The fact that beta-adrenergic blocking agents had an affinity to intraocular tissues containing melanin granules has been reported. The purpose of this study is to know that mechanism of decrease of intraocular pressure and an affinity to melanin granules of the beta-adrenergic blocking agents. Two drops of 1% befunolol were instilled in the albino and pigmented rabbits, and the eyes were enucleated on 1, 2, 6 and 24 hours after instillation. These eyes were studied with electron microscopic examination. The results were as follows 1. In the non-pigment epithelium of the ciliary body, mitochondria became swollen. 2. These changes appeared earlier and were more remarkable in albino rabbits than in pigmented ones. 3. In pigmented rabbits, these changes appeared slowly, but continued for longer duration and it seems to be due to affinity of beta-adrenergic blocking agents to the melanin pigment. 4. Swelling of mitochondria at the non-pigmented epithelium of the ciliary body after instillation of beta-adrenergic blocking agents seems to be the pharmacological mechanism of the drugs against aqueous formation in the ciliary body.