Glaucoma is a class of eye diseases associated with progressive loss of a patient's field of vision related to injury to the optic nerve. Classically, glaucoma is correlated with the pressure within the eye. There are different types of glaucoma, which are classified by the mechanism causing the pressure in the eye to rise. The primary classes of glaucoma are divided into closed (or narrow) angle glaucoma and open angle glaucoma.
How Glaucoma Affects Vision
Shown is a full, normal field of vision. With glaucoma, (place cursor over image), damage to the optic nerve will reduce the field of vision.
How does the pressure in the eye rise?
The eyeball is a closed system which makes its own fluid, called aqueous, to supply nutrients to its internal structures. In order for the eye to maintain a healthy pressure, it must also remove fluid or the pressure rises. If the pressure gets too high, the fibers which make up the optic nerve begin to die, thereby preventing the "picture" which is formed on the retina from reaching the brain - where we actually "see" an object. Your surgeon would classify narrow angle or open angle glaucoma on whether the area that drains the fluid is obstructed hence, "closed" or not "open". The open angle glaucoma is vastly more common than closed angle glaucoma.
Normally, there is an inflow and outflow of fluid within the eye (green arrows). Note the normal appearance of the optic nerve in the back of the eye. Place your cursor over the image and observe the cause and effect of glaucoma. When the fluid outflow becomes blocked (red arrows), pressure builds up (blue arrows) in the eye. This increased pressure can damage the optic nerve and result in reducing vision.
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