Open-angle glaucoma: tips for earlier detection and treatment selection

Journal of Family Practice, Feb, 2005 by Ahmad A. Aref, Brian P. Schmitt

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RELATED ARTICLE: Open-angle glaucoma: the scope of the problem.

Open-angle glaucoma (OAG) is defined as an optic neuropathy in which there is damage to the optic nerve with a loss of retinal ganglion cells that carry visual impulses from the eye to the brain. It is the second most common cause of legal blindness in the United States and the leading cause of blindness among African Americans. (2) A population-based evaluation of glaucoma screening, the Baltimore Eye Survey, estimates about 2.5 million Americans as having OAG with as many as half of them unaware that they have the disease. (3,4)

More than 8 million office visits to office-based clinicians occur per year by patients with a primary diagnosis of glaucoma. (5) The National Eye Institute, a division of the NIH, reports that as many as 120,000 Americans are currently blind as a result of glaucoma, costing the US government over $1.5 billion annually in Social Security benefits, lost income tax revenues, and health care expenditures.

An asymptomatic disease in its early stages, (1) glaucoma progresses to cause permanent blindness in the absence of treatment. This article addresses the features, diagnostic methods, and treatment modalities of glaucoma as well as the role of the family physician in its management.

What causes OAG?

The pathogenesis of glaucoma is multifactorial and is thought, in most cases, to be caused by an abnormally high intraocular pressure (IOP), which mechanically compresses and causes subsequent atrophy of optic nerve fibers. The increased pressure is due to impaired drainage of aqueous humor out of the eye. Aqueous humor, produced by the ciliary body, normally provides nutrients to the iris, lens, and cornea before being drained through the trabecular meshwork.