Glaucoma is a disease of the eye in which fluid pressure within the eye rises - if left untreated the patient may lose vision, and even become blind. The disease generally affects both eyes, although one may have more severe signs and symptoms than the other.

There is a small space in the front of the eye called the "anterior chamber". Clear liquid flows in-and-out of the anterior chamber, this fluid nourishes and bathes nearby tissues. If a patient has glaucoma, the fluid does not drain properly - it drains too slowly - out of the eye. This leads to fluid build-up, and pressure inside the eye rises. Unless this pressure is brought down and controlled, the optic nerve and other parts of the eye may become damaged, leading to loss of vision.

There are two main types of glaucoma, open angle and closed angle (angle closure) glaucoma. The fluid in the eye flows through an area between the iris and cornea, where it escapes via the trabecular meshwork - "angle" refers to this area. The trabecular meshwork is made of sponky tissue lined by trabeculocytes. Fluid drains into s set of tubes, known as Schlemm's canal, from which they flow into the blood system.

Closed Angle Glaucoma (acute angle-closure glaucoma) can come on suddenly, and the patient commonly experiences pain and rapid vision loss. Fortunately, the symptoms of pain and discomfort make the sufferer seek medical help, resulting in prompt treatment which usually prevents any permanent damage from occurring.

Primary Open Angle Glaucoma (chronic glaucoma) - progresses very slowly. The patient may not feel any symptoms; even slight loss of vision may go unnoticed. In this type of glaucoma, many people don't get medical help until some permanent damage has already occurred.

Low-tension glaucoma - this is another form that experts do not fully understand. Even though eye pressure is normal, optic nerve damage still occurs. Perhaps the optic nerve is over-sensitive or there is atherosclerosis in the blood vessel that supplies the optic nerve.

Pigmentary glaucoma -

this type generally develops during early or middle adulthood. Pigment granules, which arise from the back of the iris, are dispersed within the eye. If these granules build up in the trabecular meshwork, they can undermine the flow of fluids in the eye, leading to a rise in eye pressure. Running and some other sports can unsettle the granules, which get into the travecular meshwork.