Adrenergic Agents: Blockers and Agonists
Topical beta-blockers decrease aqueous humor formation (AHF) 1, 2 and are used long term in the therapy of the chronic open-angle glaucomas and short term for various acute glaucomas. The introduction of the topical beta-blocker timolol in 1978 was greeted with overwhelming enthusiasm not only because of the remarkable efficacy of beta-blockers but also because of the relative low frequency of ocular side effects. Before the beta-blockers, the only topical antiglaucoma medications available were the miotics and epinephrine-like compounds, the potential side effects of which will be discussed shortly. In practice, the potential ocular side effects from these latter agents resulted in an appropriate hesitancy for clinicians to treat elevated intraocular pressure (IOP), even if substantial, unless there was obvious end-organ damage (optic nerve) or abnormalities in (preautomated perimetry) visual fields. The occurrence of these side effects also adversely affected patient compliance when aggressive therapy was required for advanced glaucomatous damage.
