Glaucoma Overview

Angle-closure Glaucoma and Other Types of Glaucoma

Angle closure glaucoma is more common in the farsighted and in those of Asian descent.
Angle closure glaucoma is more common in the farsighted and in those of Asian descent.

In most cases, people with glaucoma may not even know they have it, and the irreparable damage to the optic nerve happens over time. However, in angle-closure glaucoma (also known as narrow-angle glaucoma) the pressure in the eye builds so fast that debilitating symptoms come on quickly and require prompt treatment.

In primary open-angle glaucoma, which we discussed on the previous page, the aqueous humor that nourishes the eyes reaches the trabecular meshwork located at an angle where the cornea and iris meet, but it can't drain through the meshwork. As you may be able to tell from the name, the aqueous humor can't even reach that point in angle-closure glaucoma, because the angle is closed or blocked. When this happens, the aqueous humor causes a sudden increase in eye pressure that brings on symptoms like blurred vision, headaches and nausea.

In most people, the angle where the cornea and iris meet is at about 45 degrees [source Glaucoma Foundation]. In certain people, the angle is narrower, which puts the iris very close to that crucial drain of the trabecular meshwork. The angle can also close when the pupil dilates, because it puts the lens and iris in close contact and blocks the meshwork. That's why many cases of angle closure glaucoma come when a person is stressed or in a dark room -- both of those situations cause the pupils to dilate.

When these symptoms come on, a person should seek emergency treatment to prevent blindness. But before we go over glaucoma treatment, let's examine a few other less common types of glaucoma:

  • Congenital glaucoma occurs when children are born with a defect in the angle where the trabecular meshwork is located, resulting in sensitivity in the eye, cloudy eyes and excessive tears.
  • In exfoliative glaucoma, material from other parts of the eye floats away and clogs the drain for the aqueous humor. Scientists believe that a defect in a single gene leads to this type of glaucoma [source: Wade].
  • Similarly, pigmentary glaucoma occurs when pieces of pigment break off from the iris and block the meshwork drain.
  • Neovascular glaucoma is linked to diabetes.
  • Trauma-related glaucoma occurs after an eye injury.

How is glaucoma treated? Find out on the next page.