Glaucoma is a group of diseases of the eye characterized by damage to the optic nerve, which conveys visual information in the form of electrical signals from the eye to the brain. Typically, the pathology involves abnormally high fluid pressure, known as intraocular pressure (IOP), due to excess production or impaired drainage of the aqueous humor, which is responsible for the lubricating the front part of the eye and delivering nutrition to it. If not treated in time, glaucoma can cause permanent damage to the optic nerve, loss of vision, and subsequently, blindness.
Types of glaucoma include open-angle, angle closure, and congenital. Risk factors include aging, family history, and in some cases, ethnicity. Being the second most common cause of blindness in the United States, glaucoma affects one in 200 people aged 50 and younger, and one in ten over the age of 80.
There is no known cure for the damage caused by glaucoma, and lack of treatment can have serious consequences, including loss of sight. On the other hand, the prognosis for treating glaucoma that is detected early is excellent. This reveals the importance of having regular and thorough eye examinations, as well as the responsibility of society to bring awareness to this problem. Tragically, many people afflicted with glaucoma, perhaps 50 percent, are not even aware of it, and many of these will become blind.
Understanding the types of glaucoma requires first an understanding of the mechanics of the aqueous humor, the fluid the filling anterior chamber, the front part of the eye where it bulges out with the lens, iris, and cornea. This fluid, which is produced in the back portion of the anterior chamber behind the iris and before the lens, delivers nutrients, removes metabolic wastes, and physically supports for the eye's front portion. The aqueous humor constantly replenishes itself, replacing old fluid, which exits through the anterior chamber angle (formed where the iris and cornea meet) and eventually drains into the bloodstream. Glaucoma arises because an imbalance between the drainage and production of the aqueous humor (Windle 2005) allows a build up of pressure. The elevated pressure is associated with damage to the optic nerve, but the mechanisms of that damage are not clearly understood. One hypothesis is that the elevated pressure causes a reduced blood supply to the optic nerve. There are primarily four types of glaucoma.
The most common type of glaucoma, which generally runs in one’s family, is open angle glaucoma in which, the angle between the iris and cornea gradually becomes narrow causing increased difficulties in drainage of the aqueous humor. In turn, fluid builds up causing pressure, which often leads to blind spots in the field of vision where the endings of the optic nerve have been damaged.
Open angle glaucoma mostly has no symptoms. In advanced stages, there can be loss of peripheral vision (manifestation of tunnel vision). Open angle glaucoma can potentially affect both eyes at once, and if not treated could lead to blindness.
A rare form of glaucoma that occurs when the iris’ position blocks the drainage of the aqueous humor fluid is called angle closure glaucoma. This is associated with a rapid and painful rise in intraocular pressure. Because of the severity, this should be treated as an emergency and the patient should be rushed to the doctor immediately.
Symptoms of angle closure glaucoma include:
Congenital glaucoma is often hereditary and present at birth. It is the result of abnormal development of the fluid outflow channels. Surgery is required for correction.
Symptoms of congenital glaucoma include:
Early detection of glaucoma, through examination, is very important, as a delay in treatment could have serious consequences like blindness. Because of changes in eye pressure, checking the intraocular pressure alone is insufficient. Instead, a complete and thorough eye examination is needed, in addition to the following tests:
Glaucoma is an incurable disease and damage already caused by the disorder is irreversible. However, glaucoma can be controlled through continuous treatment with medicines, laser trabeculoplasty, conventional surgery, or a combination of any of these. In some cases, treatment may need to be monitored because the disease can progress or change.
This is an original article, but some content was borrowed from Wikipedia from this version. Retrieved October 20, 2007.
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