What is angle-closure glaucoma?

Like other forms of glaucoma, angle-closure glaucoma has to do with pressure inside the eye. A normal eye constantly produces a certain amount of clear liquid called aqueous humor, which circulates inside the front portion of the eye. An equal amount of this fluid flows out of the eye through a very tiny drainage system called the drainage angle, thus maintaining a constant level of pressure within the eye.

There are two main types of glaucoma. The most common type is open-angle glaucoma, in which fluid drains too slowly from the eye and causes a chronic rise in eye pressure. In contrast, angle-closure glaucoma causes a more sudden rise in eye pressure.

In angle-closure glaucoma, the drainage angle may become partially or completely blocked when the iris (the colored part of the eye) is pushed over this area. The iris may completely block the aqueous fluid from leaving the eye, much like a stopper in a sink. In this situation, the pressure inside the eye can rise very quickly and cause an acute angle-closure glaucoma attack.