There are several types of glaucoma, but all of them cause damage to the optic nerve, the bundle of nerve fibers that carries visual information from the eye to the brain. Damage to the optic nerve can lead to vision loss or complete blindness, but early diagnosis and treatment can slow the progression of glaucoma and preserve sight.
In general, there are two categories of glaucoma: open and angle-closure glaucoma. Anatomically, the "angle" or drainage portion of the eye is normal in appearance and is in the "open" configuration whereas the opposite is true in angle-closure glaucoma.
Open Angle Glaucoma
Open-Angle Glaucoma is the most common form of glaucoma and is usually associated with an increase in eye pressure. This increase in eye pressure may be thought of as slow clogging of the aqueous humor drainage canals. But there are exceptions to this, some people have problems with their optic nerve and are at risk for developing glaucoma even when their eye pressure is within the normal range. That’s why it is important to have regular comprehensive eye examinations.
Aqueous humor is the clear liquid inside the front part of the eye. It nourishes the eye and keeps it inflated. The eye continually produces aqueous humor and it continually flows out. The production and drainage of aqueous humor is a delicate balance that must be maintained for eye health.
There are no warning signs or symptoms of Open-Angle Glaucoma during the early stages. As the disease progresses blind spots in a person’s peripheral vision will develop.
There are several other variants of Open-Angle Glaucoma. The type of treatment depends on the cause of the glaucoma. The other types are:
- Exfoliative Glaucoma occurs when dandruff-like material peels off from the outer layer of the eye's lens and clogs the drainage canals.
- Pigmentary Glaucoma occurs when pigment granules that are in the back of the iris break off and flow toward the drainage canals and slowly clog them causing eye pressure to rise.
- Neovascular Glaucoma occurs when blood vessels in the eye abnormally form over the eye’s drainage canals and cause increased eye pressure.
- Traumatic Glaucoma is caused by a blunt trauma eye injury and glaucoma can occur immediately after the injury or develop years later.
- Uveitic Glaucoma is caused by swelling and inflammation of the uvea—the middle layer of the eye.
- Congenital Glaucoma occurs in babies when there is incorrect or incomplete development of the eye’s drainage canals. It is a rare condition but can often be treated with microsurgery and medication.
Angle-Closure Glaucoma happens when the drainage angles for draining the aqueous humor suddenly become blocked and intraocular eye pressure rapidly increases. Symptoms of Angle-Closure Glaucoma are sudden and often severe eye pain, eye redness, blurred vision, sensitivity to light, and seeing rainbow halos around lights. Nausea and vomiting may also occur.
Angle-Closure Glaucoma is a medical emergency and requires immediate medical intervention. If treatment is delayed there can be permanent vision loss. Treatment is usually eye drops to lower the intraocular pressure, followed by iridotomy—surgery to open a new channel in the iris to relieve pressure.
Anyone can develop glaucoma, but certain groups are at a higher risk. Those groups include people who are over the age of 40 and from the following ethnic heritages, African, Irish, Russian, Japanese, Hispanic, Inuit, and Scandinavian, and all people over the age of 60 regardless of ethnic heritage, people with a family history of glaucoma, and people with diabetes.
If you are in a high-risk group, it’s a good idea to have a comprehensive dilated eye exam. There is no cure for glaucoma, but if it is diagnosed early there are treatments, such as prescription eye drops, laser surgery or eye surgery, that can control the disease.
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