Open Angle Glaucoma
Open angle glaucoma is the most common type of glaucoma -- it is also one of the leading causes of blindness in the United States. Symptoms tend to develop slowly; common ones include narrowed vision, gradual failure of side vision, and blindness. Although there is no cure, early detection and treatment (before major vision loss occurs) can help control the condition.
Glaucoma is a group of diseases that share certain features, namely high pressure within the eye (intraocular pressure), damage to the optic nerve, loss of peripheral (side) vision, and possibly blindness. Of all the different types, open angle glaucoma is by far the most common (see Types of Glaucoma).
The cornea is the clear outer covering of the eye. Separating it from the iris (the colored part) is the anterior chamber, a space filled and inflated by aqueous humor. This clear fluid (unrelated to the tears that bathe the outside surface of the cornea) starts in the ciliary body just behind the iris. It circulates in the anterior chamber, nourishing the eye's delicate tissue and keeping it from collapsing. To maintain equilibrium, the aqueous humor drains through a porous tissue in the angle in front of the iris, where it meets the cornea, called the trabecular meshwork.
If the aqueous humor cannot drain properly because the drainage canals become clogged (as in open angle glaucoma), it backs up, putting pressure on the gel in the vitreous cavity at the center of the eye. Eventually, the building pressure affects the delicate optic nerve at the rear of the eye. Since the optic nerve transmits visual images to the brain, any damage to it reduces vision.
The optic nerve is a bundle of more than one million nerve fibers. It connects the retina to the brain. The retina is the light-sensitive tissue at the back of the eye. A healthy optic nerve is necessary for good vision.