The eye is under constant intraocular pressure (IOP) that increases in patients who have glaucoma. This increased pressure damages the optic nerve resulting in decreased peripheral vision and eventually blindness.

About three million Americans have glaucoma, 120,000 of them have lost their eyesight. Glaucoma is the leading cause of blindness. There are two types of glaucoma: chronic (primary) open-angle glaucoma (POAG) and acute closed-angle glaucoma.

Chronic open-angle glaucoma

Chronic open-angle glaucoma is the most common form of glaucoma. The "open" drainage angle of the eye can become blocked leading to a gradual increase in eye pressure. If this increased pressure results in optic nerve damage, it is known as chronic open-angle glaucoma. The optic nerve damage and vision loss usually occurs so gradually and painlessly that you are not aware of trouble until the optic nerve is already badly damaged.

Angle-closure glaucoma

Angle-closure glaucoma results when the drainage angle of the eye narrows and becomes completely blocked. In the eye, the iris may close off the drainage angle and cause a dangerously high eye pressure. When the drainage angle of the eye suddenly becomes completely blocked, pressure builds up rapidly, and this is called acute angle-closure glaucoma. The symptoms include severe eye pain, blurred vision, headache, rainbow haloes around lights, nausea, and vomiting. Unless an ophthalmologist treats acute angle-closure glaucoma quickly, blindness can result. When the drainage angle of the eye gradually becomes completely blocked, pressure builds up gradually, and this is called chronic angle-closure glaucoma. This form of glaucoma occurs more frequently in people of African and Asian ancestry, and in certain eye conditions.

Acute angle-closure glaucoma is a medical emergency. If IOP is not reduced within hours of onset, the patient's vision can be permanently damaged.

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