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Glaucoma is an acquired chronic optic neuropathy characterized by optic disk cupping and visual field loss. It is usually associated with elevated intraocular pressure. There are different types of glaucoma (Table 11–1), which helps to explain, for example, why one patient with glaucoma may have no symptoms, while another experiences sudden pain and inflammation. In the majority of cases, there is no associated ocular disease (primary glaucoma).

Table 11-1. Glaucoma Classified According to Etiology

About 60 million people have glaucoma. An estimated 3 million Americans are affected, and of these cases, about 50% are undiagnosed. About 6 million people are blind from glaucoma, including approximately 100,000 Americans, making it the leading cause of preventable blindness in the United States. Primary open-angle glaucoma, the most common form among blacks and whites, causes insidious asymptomatic progressive bilateral visual loss that is often not detected until extensive field loss has already occurred. Blacks are at greater risk than whites for early onset, delayed diagnosis, and severe visual loss. Angle-closure glaucoma accounts for 10%–15% of cases in whites. This percentage is much higher in Asians and Inuit. Primary angle-closure glaucoma may account for over 90% of bilateral blindness due to glaucoma in China. Normal-tension glaucoma is the most common type in Japan.

The mechanism of raised intraocular pressure in glaucoma is impaired outflow of aqueous resulting from abnormalities within the drainage system of the anterior chamber angle (open-angle glaucoma) or impaired access of aqueous to the drainage system (angle-closure glaucoma) (Table 11–2). Treatment is directed toward reducing the intraocular pressure and, when possible, correcting the underlying cause. Although in normal-tension glaucoma intraocular pressure is within ...

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