Glaucoma (patient information): Difference between revisions
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Revision as of 05:59, 23 August 2012
For the WikiDoc page for this topic, click here
| Glaucoma (patient information) | |
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| The pink rim of disc contains nerve fibers. The white cup is a pit with no nerve fibers. As glaucoma advances, the cup enlarges until it occupies most of the disc area. Courtesy AgingEye Times | |
| ICD-10 | H40-H42 |
| ICD-9 | 365 |
| DiseasesDB | 5226 |
| MeSH | D005901 |
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Glaucoma |
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Glaucoma On the Web |
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Assistant Editor(s)-In-Chief: Erin E. Lord;
Overview
Glaucoma is a disease in which the optic nerve is damaged, leading to progressive, irreversible loss of vision. It is often, but not always, associated with increased pressure of the fluid in the eye. It is possible to have increased eye pressure without having glaucoma, as well as having glaucoma without increased eye pressure.
Glaucoma is the second most common cause of blindness in the United States. There are many types of glaucoma, including:
- Open-angle (chronic) glaucoma
- Angle-closure (acute) glaucoma
- Low-tension or normal-tension glaucoma
- Congenital glaucoma
- Secondary glaucoma (including Pigmentary glaucoma and Neovascular glaucoma)
What are the symptoms of glaucoma?
Symptoms of glaucoma vary greatly, depending on the type of disease present.
Open-angle glaucoma
- Most people have no symptoms until they begin to lose vision
- Gradual loss of peripheral (side) vision (also called tunnel vision)
Angle-closure glaucoma
- Symptoms may come and go at first, or steadily become worse
- Sudden, severe pain in one eye
- Decreased or cloudy vision
- Nausea and vomiting
- Rainbow-like halos around lights
- Red eye
- Eye feels swollen
Low-tension or normal-tension glaucoma
- Narrowed side vision in people with normal eye pressure
Congenital glaucoma
- Symptoms are usually noticed when the child is a few months old
- Cloudiness of the front of the eye
- Enlargement of one eye or both eyes
- Red eye
- Sensitivity to light
- Excessive Tearing
What are the causes of glaucoma?
The four major types of glaucoma have their own unique causes. However, before reviewing them, a brief overview of the anatomy of the eye may be helpful in understanding the causes of this disease:
The front part of the eye is filled with a clear fluid called aqueous humor. This fluid is always being made in the back of the eye. It leaves the eye through channels in the front of the eye in an area called the anterior chamber angle, or simply the angle. Anything that slows or blocks the flow of this fluid out of the eye will cause pressure to build up in the eye. This pressure is called intraocular pressure (IOP). In most cases of glaucoma, this pressure is high and causes damage to the major nerve in the eye, called the optic nerve.
More specific causes by each major type of glaucoma are:
Open-angle (chronic) glaucoma
- The cause is unknown. An increase in eye pressure occurs slowly over time. The pressure pushes on the optic nerve and the retina at the back of the eye.
- Open-angle glaucoma tends to run in families. Your risk is higher if you have a parent or grandparent with open-angle glaucoma. People of African descent are at particularly high risk for this disease.
Angle-closure (acute) glaucoma
- It occurs when the exit of the aqueous humor fluid is suddenly blocked.
- Dilating eye drops and certain medications may trigger an acute glaucoma attack.
Congenital glaucoma
- It is present at birth and results from the abnormal development of the fluid outflow channels in the eye.
- It is often hereditary and tends to run in families.
Secondary glaucoma
- It is caused as complications of other medical conditions and/or procedures, including eye surgery, advanced cataracts, eye injuries, certain eye tumors, and uveitis. [1]
- It can be caused by drugs such as corticosteroids, which are used to treat eye inflammations.
- Pigmentary glaucoma is caused when pigment from the iris breaks off, thereby slowing the fluid drainage and blocking the meshwork.
- Neovascular glaucoma is a severe form of secondary glaucoma that is linked to diabetes.[2]
Who is at highest risk?
Anyone can develop glaucoma, however some people are at higher risk than others. The most important risk factor for glaucoma is ocular hypertension. Individuals at a higher risk of developing glaucoma include:
- African Americans over age 40.
- Everyone over age 60, especially Mexican Americans.
- People with a family history of glaucoma.
Among African Americans, studies show that glaucoma is:
- Five times more likely to occur in African Americans than in Caucasians.
- About four times more likely to cause blindness in African Americans than in Caucasians.
- Fifteen times more likely to cause blindness in African Americans between the ages of 45-64 than in Caucasians of the same age group.
A comprehensive dilated eye exam can reveal more risk factors, such as:
- High eye pressure
- Thinness of the cornea
- Abnormal optic nerve anatomy.
In some people with certain combinations of these high-risk factors, medicines in the form of eye drops reduce the risk of developing glaucoma by about half.
How to know you have glaucoma?
A comprehensive eye exam is necessary to determine whether a patient has glaucoma. Checking the intraocular pressure alone (tonometry) is not enough to diagnose glaucoma because eye pressure changes. Furthermore, pressure in the eye is normal in about 25% of people with glaucoma (normal-tension glaucoma). There are other problems that cause optic nerve damage.
Tests to diagnose glaucoma include may:
- Gonioscopy (use of a special lens to see the outflow channels of the angle)
- Tonometry test to measure eye pressure
- Optic nerve imaging (photographs of the inside of the eye)
- Pupillary reflex response
- Retinal examination
- Slit lamp examination / Dilated eye exam
- Visual acuity
- Visual field measurement
- Pachymetry
When to seek urgent medical care
Call your health care provider if you have severe eye pain or a sudden loss of vision, especially loss of peripheral 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.
Treatment options
The goal of treatment is to reduce eye pressure. Depending on the type of glaucoma, this is done using medications or surgery.
Open-angle glaucoma treatment
Most people with open-angle glaucoma can be treated successfully with eye drops. Most eye drops used today have fewer side effects than those used in the past. You may need more than one type of drop. Some patients may also be treated with pills to lower pressure in the eye. Newer drops and pills are being developed that may protect the optic nerve from glaucoma damage.
Some patients will need other forms of treatment, such as a laser treatment, to help open the fluid outflow channels. This procedure is usually painless. Others may need traditional surgery to open a new outflow channel.
Angle-closure glaucoma treatment
Acute angle-closure attack is a medical emergency. Blindness will occur in a few days if it is not treated. Drops, pills, and medicine given through a vein (by IV) are used to lower pressure. Some people also need an emergency operation, called an iridotomy. This procedure uses a laser to open a new channel in the iris. The new channel relieves pressure and prevents another attack.
Congenital glaucoma treatment
This form of glaucoma is almost always treated with surgery to open the outflow channels of the angle, as medicines may have unknown effects in infants and be difficult to administer.
Where to find medical care for glaucoma
Directions to Hospitals Treating glaucoma
Prevention of glaucoma
There is no way to prevent open-angle glaucoma, but you can prevent vision loss from the condition. Early diagnosis and careful management are the keys to preventing vision loss.
Most people with open-angle glaucoma have no symptoms. Everyone over age 40 should have an eye examination at least once every 5 years, and more often if in a high-risk group. Those in high-risk groups include people with a family history of open-angle glaucoma and people of African heritage. Such high-risk groups should have a comprehensive dilated eye exam at least once every two years.
People at high risk for acute glaucoma may opt to undergo iridotomy before having an attack. Patients who have had an acute episode in the past may have the procedure to prevent a recurrence.
What to expect (Outlook/Prognosis)?
Untreated glaucoma leads to permanent damage of the optic nerve and resultant visual field loss, which can progress to blindness.
The outlook of the disease varies by type:
Open-angle glaucoma
With good care, most patients with open-angle glaucoma can manage their condition and will not lose vision, but the condition cannot be cured. It's important to carefully and regularly follow up with your doctor.
Angle-closure glaucoma
Rapid diagnosis and treatment of an attack is key to saving your vision. Seek emergency care immediately if you have symptoms of an angle-closure attack, as blindness will occur in a few days if it is not treated.
Congenital glaucoma
Early diagnosis and treatment is important. If surgery is done early enough, many patients will have no future problems.
Additional links
http://www.nlm.nih.gov/medlineplus/ency/article/001620.htm http://www.nei.nih.gov/health/glaucoma/glaucoma_facts.asp