What causes glaucoma?

In most cases of primary glaucoma, there is no identifiable cause except a possible hereditary predisposition. The basic shape of the eye may predispose some people to develop some types of glaucoma.

Aqueous humor is a clear fluid that is continuously produced inside the eye. This fluid circulates within the eye, nourishing it and removing waste products. The fluid drains from the eye through a sieve called the trabecular meshwork.

From the trabecular meshwork, the fluid empties into a drainage canal, called the Canal of Schlemm, and then into the blood stream.

These drainage structures are located in an area of the eye called the anterior chamber angle, where the cornea and iris come together. Fluid inside the eye does not drain into tears.

The process of making and draining fluid maintains a certain intraocular pressure necessary for the health of your eyes. Glaucoma develops when the eye's ability to drain fluid decreases. This results in a buildup of pressure throughout the eye. The increased pressure causes damage to the optic nerve, which eventually can lead to loss of vision.