Open-angle glaucoma is the most common form of the disease and generally does not affect people until they are in their 40s. But there are other types that can strike earlier-some even start in childhood.
In closed-angle glaucoma, the inside of the eye is too crowded. There is not enough room for the normal flow of aqueous humor, either through or out of the eye. The fluid has problems passing from behind the iris (colored part of the eye), through the pupil (the hole in the center of the iris), and to the anterior chamber (the fluid-filled area between the iris and the cornea, which is the clear front part of the eye through which light passes). The fluid just won't drain properly, which can lead to two serious problems:
- Acute angle-closure glaucoma. reasons not known, the eye pressure increases rapidly. The person notices eye pain, eye redness, blurred vision, and haloes around lights. This is often accompanied by nausea and vomiting. Since the pressure can lead to blindness, this is a real emergency and requires an immediate visit to the doctor or emergency department.
No one knows why, but acute glaucoma tends to be more common among middle-aged women. And just as open-angle glaucoma is more common among blacks, acute glaucoma tends to be more prevalent in Eskimos and in the people of Southeast Asia than in other races.
Doctors will sometimes use a hyperosmotic agent, a sugar-based medication, to quickly lower eye pressure. It is a temporary measure and not useful for long-term treatment.
- Chronic angle-closure glaucoma. The drainage tissues gradually start to scar. This blocks the flow of fluid, and the eye pressure rises slowly. This condition is generally silent, and severe glaucoma damage can occur without the person's knowledge.
People suffering from closed-angle glaucoma might need an
iridotomy, a lasersurgical procedure. A small hole is created in the iris, which improves fluid flow through the eye and reverses the crowding problem that causes the condition. This is a painless outpatient procedure that only takes a few minutes and has few complications. If a person needs treatment in one eye, it will most likely be needed in the other.
Neovascular glaucoma develops when blood vessels grow in the front part of the inside of the eye. This abnormal growth can block the drainage channels, which leads to a pressure buildup.
This type of glaucoma can develop as a result of diabetes, insufficient blood flow to the arteries in the neck, or as a result of other eye conditions.
Once neovascular glaucoma is fully developed, it is extremely difficult to treat and usually results in irreversible vision loss. So, it is best to prevent it or treat it as soon as possible.
Although eye drops and pills may help, laser surgery is usually the treatment of choice. A laser will sometimes cause the abnormal blood vessels to disappear. If it is done early enough, eye pressure may return to normal with little or no permanent damage. In eyes in which the eye pressure remains high despite laser treatment and medicine, conventional surgery may be performed to open up the draining channels.
Pigment dispersion glaucoma and exfoliation glaucoma are both similar to open-angle glaucoma. What sets them apart is the presence of abnormalities in the front part of the eye.
- In pigment dispersion glaucoma, pigment is lost from the iris and is deposited on other structures, including the drainage channels. It is more common in younger persons, in males, and in near-sighted people.
- In exfoliation syndrome glaucoma, abnormal deposits are found on the surface of the lens and on other structures inside the eyeball. This can sometimes lead to a rapid increase of eye pressure. It is more common in older people and among people of Scandinavian descent.
Both are treated in much the same way as open-angle glaucoma.
Normal-pressure, or low-pressure, glaucoma is sometimes called low-tension glaucoma. It is the type of glaucoma that develops where there is no increase in eye pressure. Many experts say that people who develop this condition have unusually sensitive optic nerves. But other factors-still unknown-may also contribute to their damage. This type of glaucoma is treated by lowering the eye pressure.