Glaucoma affects approximately 3 million Americans and over 120,000 will go blind from this disease. Glaucoma ranks as a leading cause of blindness worldwide. Even if it does not cause blindness, it can severely impair vision.
There are often no warning signs of glaucoma. About half of Americans with chronic glaucoma don’t know they have it. Glaucoma gradually reduces the peripheral vision ultimately resulting in tunnel-like vision. Once vision is lost, it cannot be regained.
Glaucoma is a culmination of three factors: increased intraocular pressure which causes permanent damage to optic nerve head, which results in loss of visual field. Early detection and treatment are the keys to preventing optic nerve damage and blindness from glaucoma.
Clear liquid, called the aqueous humor, circulates inside the eye. The eye is constantly producing a small amount of this fluid and an equal amount flows out of the eye through a microscopic drainage system. (This liquid is not part of the tears on the outer surface of the eye.)
The process of acquits humor production and draining is analogous to a bathtub with the drain open and faucet turned on all the time. If the faucet is flowing faster than the water is draining from the tub, the tub will overflow. In the eye, if the rate of aqueous formation in the eye supposes the rate at which the aqueous drains, the pressure in the eye (the intraocular pressure) will increase. A high pressure in the eye can result in chronic damage to the optic nerve head.
There are two major types of glaucoma: Open angle glaucoma and Angle closure glaucoma. Chronic open angle glaucoma is the most common form of glaucoma in the United States and occurs as a result of again changes and “narrowing” of the draining system of the eye. While the drainage system is still open, or patent, the rate at which the fluid is drained is greatly diminished. As the drainage system losses efficiency, the pressure within the eye gradually increases and causes progressive damage to the optic nerve. There are very few symptoms associated with chronic open-angle glaucoma. Peripheral vision is lost so gradually and painlessly that the patient is often not not aware of any changes until the optic nerve is already badly damaged.
In contrast to chronic open angle glaucoma, Angle-closure glaucoma is due to a complete blockage either acutely, over a period of hours-to-days, of chronically, over years. A sudden, complete closure of the drainage apparatus of the eye causes an acute increase in intraocular pressure and results in symptoms of blurred vision, severe eye pain, headache, rainbows and halos around lights, nausea and vomiting.
An ophthalmologist must evaluate each patient to determine the status of the angle and the function of the drainage system of the eye.
The progression of glaucoma can be monitored through serial measurements of intraocular pressure, as well as through monitoring visual fields and with specialized measurements of the optic nerve head.
While damage caused by glaucoma cannot be reversed, eye drops, pills, lasers, and surgical operations can be used to prevent and slow the progression of glaucoma.