Glaucoma
Posted: Wednesday, April 21, 2010
by Melissa Burkley
Melissa J. Burkley, O.D.
Glaucoma is a disease of the optic nerve that can lead to blindness. There is a fluid in the eye called aqueous humor. The purpose of this fluid is to keep your eye firm so that it doesn't collapse in on it's self. Glaucoma is developed when there is too much of this fluid in the eye either because the body is producing too much or not draining the fluid properly. Over time this fluid preesure will start to pound on the optic nerve head. The optic nerve head head is where the optic nerve exits the back of the eye forming the optic nerve which sends the visual signals to the brain. Typically both eyes are affected equally unless there has been trauma that causes it to develop in one eye only. In the United States approximately 2.2 million people age 40 and older have glaucoma and of these as many as 120,000 are blind due to the disease.
The direct or binocular indirect ophthalmoscope allows us to look directly at the optic nerve to see if deterioration has taken place which is the definitive sign of having glaucoma. The optic nerve has a cup to disc ratio. This ratio should be around .2. when a patient is diagnosed with glaucoma this ratio is usually .6 or higher. When the ratio reaches .9 the patient has endstage glaucoma meaning they are effectively blind at that point.
Other testing for glaucoma includes visual field testing and optic nerve computer imaging. These tests are usually only done after you have been diagnosed with the disease.
Anyone can get glaucoma. But some people are more likely to get it. Risk factors include the following :
Increasing age You are six times more likely to get glaucoma if you are over 60 years of age.
African ancestry Glaucoma is the leading cause of blindness among African-Americans. It is six to eight times more common in African-Americans than in Caucasians.
A Family history of glaucoma Family history increases your risk of glaucoma four to nine times.
Previous eye injuries or surgeries Injury to the eye can cause secondary open angle glaucoma. This type of glaucoma can occur immediately after the injury or years later
Health problems such as diabetes or high blood pressure
Other possible risk factors are high myopia also known as nearsightedness and central cornea thickness less than .5 mm
Gender the evidence is still conflicting on whether or not glaucoma affects men or women the most. However there is one study that found up to a twofold higher prevalence in men.
There are several different types of glaucoma but the two main kinds are Open-Angle Glaucoma and Closed-Angle Glaucoma.
Open-Angle Glaucoma is the most common. It occurs slowly as people age. The drainage area in the eye becomes clogged. Not enough fluid drains from the eye, so pressure slowly builds up. This causes loss of side(peripheral) vision. But the loss is so gradual that you may not notice it, hence the importance of your annual eye exam. The drainage area of people with African ancestry can become clogged with pigment which is why their chances of getting glaucoma is higher.
Closed-Angle Glaucoma is less common. It usually comes on quickly. The drainage area in the eye suddenly becomes completely blocked. Eye pressure builds rapidly. You may notice blurred vision and rainbow halos around lights. You may also have headaches, nausea, vomiting and severe pain. If not treated right away blindness can occur quickly.
Congenital Glaucoma is usually diagnosed within the first year of life. This is a rare condition that may be inherited, caused by incorrect development of the eyes drainage sysytem before birth. This leads to increased intraocular pressure which in turn damages the optic nerve. Symptoms of childhood glaucoma include enlarged eyes, cloudinessof the cornea, and sensitivity to light. In uncomplicated cases surgery can often correct the structural defects. In some cases both medication and surgery are required.
Normal Tension Glaucoma is when the pressure is normal, however, there is damage to the optic nerve. Family history, Japanese ancestry and people with heart problems increase the chances of developing this type of glaucoma.
The doctor will try to keep the pressure as low as possible in such cases.
Unfortunately, glaucoma is not preventable or curable, however it is treatable.
Treatment of glaucoma is either by eye drops or pills which is usually the first approach, or with surgery as the secondary approach. There are several different drops that the doctor may choose to treat a patient with glaucoma . Three of the most commonly prescribed medications include:
Prostaglandins such as Xalatan, Lumigan and Travatan increase outflow of aqueous humor.
Beta-Blockers such as Timolol and Betagan decrease aqueous humor production by the ciliary body.
Carbonic Anhydrase Inhibitors like Trusopt, Azopt, and Diamox also lower the secretion of aqueous humor.
If the intraocular pressure is not successfully lowered by medication then usually the next step is to perform surgery. Three of the most common surgeries include:
Trabeculectomy a partial thickness flap is made in the scleral wall of the eye, and a window opening made under the flap to remove a portion of the trabecular meshwork. The scleral flap is then sutured loosely back in place. This allows fluid to flow out of the eye through this opening, resulting in lower intraocular pressure and the formation of a bleb or a
fluid bubble on the surface of the eye.
Laser trabeculoplasty an argon laser spot is aimed at the trabecular meshwork to stimulate opening of the mesh to allow more outflow of aqueous fluid.
Laser Peripheral Iridotomy can be used in patients susceptible to or affected by angle closure glaucoma or pigment dispersion syndrome. Laser energy is used to make a small full thickness opening in the iris, which equalizes the pressure between the front and the back of the iris.
There are some dietary supplements of research interest in the prevention or treatment of glaucoma. A few of these include fish oil, omega 3 fatty acids, vitamin E, folic acid and green tea.
One of the most important things to remember about glaucoma is that there really are no warning signs that you will experience until most of peripheral vision has been destroyed and you have what is called tunnel vision meaning that you can only see what is directly in front of you. Therefore it is imperative to get annual eye exams so that if you do develop glaucoma it can be detected early.
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Top-level comments on this article: (7 total)I hear glaucoma is super painful, doesnt sound like fun and I glad I dont suffer from it.It is only painful when your pressure is extremely high but for the most part it is a silent disease.
I learned from you, Melissa. For one thing, I never someone as young as 40 could be at risk. Good article and welcome to SearchWarp.Lorrie thank you so much for the welcome and I am glad that you enjoyed the article. Please feel free to send me any advice you may have or any eye related questions that you may have that I could write an article on.Have a great dayMelissa
Welcome to Searchwarp and thanks for a most informative article on glaucomaThank you so much for welcoming me and I am glad that you enjoyed the article. As I am new I would love any suggestions you may have or any eye related questions you would like me to write an article on. Enjoy your day.Melissa
Melissa, thanks for this hugely informative article. My grandmother had glaucoma, and so does my mother. My sight has got blurry lately and I've been too scared to check it out, but you've prompted me to go and get that test done. Thanks!
Very good information. Maybe too long. Thank you for the information. Jack
Very interesting article on a topic that one would generally not know much about or even read. Though it is pretty technical, Melissa has written the article in a very down to basic language. Good work.
A lot of very detailed information. Very interesting article thanks.
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