12 April 2011


Glaucoma involves increased fluid pressure inside the eye (intraocular pressure), which damages the optic nerve and causes partial vision loss and can progress to blindness.
Glaucoma develops when the production of aqueous humor (fluid in the eye) increases or the aqueous humor does not drain adequately. The pressure rises in the eye. Nerve fibers and blood vessels in the optic nerve become compressed and can be damaged or destroyed. Consequently, the transmission of visual messages to the brain is interrupted. The result is impaired vision and, ultimately, blindness. Why does glaucoma happen? What are the types of glaucoma?
There are different varieties of glaucoma, all of which involve a build-up of pressure inside the eye. Glaucoma can sometimes result from other eye conditions such as inflammation or injury. Rarely, infants are born with the disease. However, chronic and acute glaucoma are by far the most common form.
Tests to diagnose glaucoma
1. Visual acuity: This eye chart test measures how well you see at various distances.
2. Visual Field: This test measures your side (peripheral) vision. It helps your eye care professional find out if you have lost side vision, a sign of glaucoma.
3. Pupil dilation: This examination provides your eye care professional with a better view of the optic nerve to check for signs of damage. To do this, your eye care professional places drops into the eye to dilate (widen) the pupil. After the examination, your close-up vision may remain blurred for several hours.
4. Tonometry: This standard test determines the fluid pressure inside the eye. There are many types of tonometry.
What are the types of glaucoma?
There are four major types of glaucoma:
Closed angle (acute) glaucoma
Open angle (chronic) glaucoma
Congenital glaucoma
Secondary glaucoma
All four types of glaucoma are characterized by increased pressure within the eyeball, and therefore all can cause progressive damage to the optic nerve.
Increased pressure occurs when the fluid within the eye (called aqueous humor) does not drain properly. The pressure pushes on the junction of the optic nerve and the retina at the back of the eye. This reduces the blood supply to the optic nerve, which carries visual information from the eye to the brain.

Glaucoma Symptoms & Signs
Severe eye pain, facial pain
Loss of vision
Cloudy vision with halos appearing around lights
Red eye
Fixed, nonreactive pupil
Nausea and vomiting
Gradual loss of peripheral vision
Blurred or foggy vision
Mild, chronic headaches
Seeing rainbow-colored halos around lights
Note: Most people with chronic glaucoma have no symptoms until peripheral visual loss is severe
Sensitivity to light
Redness of the eye
Corneal haziness
Enlarged cornea
Glaucoma Prevention
There is no prevention for the development of open angle glaucoma. If detected early, further vision loss and blindness may be prevented with treatment. Patients with risk factors for closed angle glaucoma should be evaluated and those at high risk should have laser iridotomy, which will prevent acute attacks.
Careful use of dilating eye drops and systemic anticholinergic medications will minimize the risk of acute attacks in high-risk individuals.
Anyone older than 35 should have tonometry (a check of intraocular pressure) and ophthalmoscopy examinations every 2 years. More frequent examination is recommended for people who have a family history of glaucoma or other risk factors and/or are African-American.
Glaucoma Treatment
The objective of treatment is to reduce the intraocular pressure. Depending on the type of glaucoma, this is achieved by medications or by surgery.MEDICATIONS:
Acute glaucoma is a medical emergency requiring immediate treatment by an emergency center or an ophthalmologist. Intraocular pressure can usually be lowered by medications that may be given orally, intravenously, or topically (as eye drops).
This topical medication helps drain the aqueous outflow from the eye and lower the intraocular pressure. Oral medication or topical drops may be prescribed separately, or a combination of both may be used.

Some types of glaucoma (e.g., angle closure glaucoma) may indicate surgery as a first-line therapy. Other types (e.g., primary open angle glaucoma) might initially be treated with medication to control damage and then later with surgery.
A glaucoma surgeon must evaluate the patient and decide which type of surgery is best. Surgeries for glaucoma may be performed using laser or conventional surgical instruments.
Laser surgeries use a concentrated beam of light to open the flow of aqueous out of the eye and thus decrease intraocular pressure. The two most common glaucoma laser surgeries are (1) trabeculoplasty and (2) iridotomy. A trabeculoplasty is most often used for open angle glaucoma and uses a laser to place new holes in the drainage area of the eye to allow the aqueous to drain more freely. A iridotomy is used to treat angle-closure glaucoma. This laser procedure makes a small hole in the iris of the eye to allows the aqueous to flow more freely and tries to prevent the iris from plugging up the drainage system called the trabecular meshwork.
Most laser surgeries are performed in the doctor's office with little discomfort during the procedure. Mild eye irritation is usually the only symptom after surgery. Most patients can resume normal activities within a day or two.
Laser surgery may not be the answer to treat all glaucoma patients. When vision loss by glaucoma is rapid or medication and/or laser surgery fails to lower IOP sufficiently, conventional surgery may be the best option.
The most common conventional surgical procedure is called filtering surgery. Filtering surgery is usually done in a hospital or outpatient surgery center. A tiny piece of the white part of the eye (the sclera) is removed leaving a small hole. The aqueous can then drain through the hole and be reabsorbed into the bloodstream. This in turn decreases intraocular pressure.
There are some instances where surgery alone does not completely work. Some patients may have to return to medication and some may need additional surgery to prevent any further loss of vision.
Glaucoma Prognosis (Expectations)
Untreated acute glaucoma results in severe and permanent vision loss after the onset of symptoms. Vision can be preserved with prompt treatment. Untreated chronic glaucoma can progress to blindness within 20 to 25 years. Early diagnosis and treatment have excellent success with preserving vision. Treatment prevents further loss, but does not bring back vision already lost.The outcome for congenital glaucoma varies depending on the age when symptoms begin.
Calling Your Health Care Provider
Call your health care provider if you have severe eye pain or a sudden loss of vision, especially loss of lateral (away from the middle) vision.Call for an appointment with your health care provider if you have risk factors for glaucoma and have not been screened for the condition.

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