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Glaucoma
Definition
Glaucoma refers to a group of eye conditions that lead to damage to the optic nerve. This nerve carries visual information from the eye to the brain.
In most cases, damage to the optic nerve is due to increased pressure in the eye, also known as intraocular pressure (IOP).
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Alternative Names
Open-angle glaucoma; Chronic glaucoma; Chronic open-angle glaucoma; Primary open-angle glaucoma; Closed-angle glaucoma; Narrow-angle glaucoma; Angle-closure glaucoma; Acute glaucoma; Secondary glaucoma; Congenital glaucoma
Causes
Glaucoma is the second most common cause of blindness in the United States. There are four major types of glaucoma:
- Open-angle (chronic) glaucoma
- Angle-closure (acute) glaucoma
- Congenital glaucoma
- Secondary glaucoma
The front part of the eye is filled with a clear fluid called aqueous humor. This fluid is always being made behind the colored part of the eye (the iris). 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 optic nerve.
Open-angle (chronic) glaucoma is the most common type of glaucoma.
- The cause is unknown. An increase in eye pressure occurs slowly over time. The pressure pushes on the optic nerve.
- 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 occurs when the exit of the aqueous humor fluid is suddenly blocked. This causes a quick, severe, and painful rise in the pressure in the eye.
- Angle-closure glaucoma is an emergency. This is very different from open-angle glaucoma, which painlessly and slowly damages vision.
- If you have had acute glaucoma in one eye, you are at risk for an attack in the second eye, and your doctor is likely to recommend preventive treatment.
- Dilating eye drops and certain medications may trigger an acute glaucoma attack.
Congenital glaucoma is seen in babies. It often runs in families (is inherited).
- It is present at birth.
- It is caused by abnormal eye development.
Secondary glaucoma is caused by:
- Drugs such as corticosteroids
- Eye diseases such as uveitis
- Systemic diseases
- Trauma
Symptoms
OPEN-ANGLE GLAUCOMA
- Most people have no symptoms
- Once vision loss occurs, the damage is already severe
- There is a slow loss of side (peripheral) vision (also called tunnel vision)
- Advanced glaucoma can lead to blindness
ANGLE-CLOSURE GLAUCOMA
- Symptoms may come and go at first, or steadily become worse
- Sudden, severe pain in one eye
- Decreased or cloudy vision, often called "steamy" vision
- Nausea and vomiting
- Rainbow-like halos around lights
- Red eye
- Eye feels swollen
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
- Tearing
Exams and Tests
A complete eye exam is needed to diagnose glaucoma. You may be given eye drop to widen (dilate) your pupil. The eye doctor can look at the inside of the eye when the pupil is dilated.
A test called (tonometry) is done to check eye pressure. However, eye pressure always changes. Eye pressure can be normal in some people with glaucoma. This is called normal-tension glaucoma. Your doctor will need to run other tests to confirm glaucoma.
Some of the tests your doctor may do can include:
- Using a special lens to look at the eye (gonioscopy)
- Photographs or laser scanning images of the inside of the eye (optic nerve imaging)
- Examination of the retina in the back of the eye
- Slit lamp examination
- Visual acuity
- Visual field measurement
Treatment
The goal of treatment is to reduce eye pressure. Treatment depends on the type of glaucoma that you have.
If you have open-angle glaucoma, you will probably be given eye drops. You may need more than one type. Most people can be treated successfully with eye drops. Most of the eye drops used today have fewer side effects than those used in the past. You may also be given pills to lower pressure in the eye.
Other treatments may involve:
- Laser therapy called an iridotomy
- Eye surgery if other treatments do not work
Acute angle-closure attack is a medical emergency. Blindness will occur in a few days if it is not treated. If you have angle-closure glaucoma, you will receive:
- Eye drops
- Medicines to lower eye pressure, given by mouth and through a vein (by IV)
Some people also need an emergency operation, called an iridotomy. This procedure uses a laser to open a new pathway in the colored part of the eye. This relieves pressure and prevents another attack.
Congenital glaucoma is almost always treated with surgery. This is done using general anesthesia. This means the patient is asleep and feels no pain.
If you have secondary glaucoma, treatment of the underlying disease may help your symptoms go away. Other treatments may be needed.
Outlook (Prognosis)
Open-angle glaucoma cannot be cured. However, you can manage your symptoms by closely following your doctor's instructions. Regular check-ups are needed to prevent blindness.
Angle-closure glaucoma is a medical emergency. You need treatment right away to save your vision.
Babies with congenital glaucoma usually do well when surgery is done early.
How well a person with secondary glaucoma does depends on the disease causing the condition.
When to Contact a Medical Professional
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.
Prevention
All adults should have a complete eye exam before age 40, or sooner if you have risk factors for glaucoma or other eye problems. You are more likely to get glaucoma if you are African American or have a family history of open-angle glaucoma.
If you are at high risk for acute glaucoma, talk to your doctor about having eye surgery to prevent an attack.
References
Anderson DR. The Optic Nerve in Glaucoma. In: Tasman W, Jaeger EA, eds. Duane’s Ophthalmology. 15th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2009:chap 48.
Kwon YK, Caprioli J. Primary Open-Angle Glaucoma. In: Tasman W, Jaeger EA, eds. Duane’s Ophthalmology. 15th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2009:chap 52.
Giaconi JA, Law SK, Caprioli J. Primary Angle-Closure Glaucoma. In: Tasman W, Jaeger EA, eds. Duane’s Ophthalmology. 15th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2009:chap 53.
Mandelcorn E, Gupta N. Lens-Related Glaucomas. In: Tasman W, Jaeger EA, eds. Duane’s Ophthalmology. 15th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2009:chap 54A.
Reviewed By: Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington, School of Medicine; Franklin W. Lusby, MD, Ophthalmologist, Lusby Vision Institute, La Jolla, California. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
