Most often, optic nerve damage is caused by increased pressure in the eye. This is called intraocular pressure.
Glaucoma is the second most common cause of blindness in the U.S. There are four major types of glaucoma:
- Open-angle glaucoma
- Angle-closure glaucoma, also called closed-angle glaucoma
- Congenital glaucoma
- Secondary glaucoma
The front part of the eye is filled with a clear fluid called aqueous humor. This fluid is made in an area behind the colored part of the eye (iris). It leaves the eye through channels where the iris and cornea meet. This area is called the anterior chamber angle, or the angle. The cornea is the clear covering on the front of the eye that covers the iris, pupil, and angle.
Anything that slows or blocks the flow of this fluid will cause pressure to build up in the eye.
- In open-angle glaucoma, the increase in pressure is often small and slow.
- In closed-angle, the increase is often high and sudden.
- Either type can damage the optic nerve.
Open-angle glaucoma is the most common type of glaucoma.
- The cause is unknown. The increase in eye pressure happens slowly over time. You can’t feel it.
- The increased pressure pushes on the optic nerve. Damage to the optic nerve causes blind spots in your vision.
- 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 also at higher risk for this disease.
Closed-angle glaucoma occurs when the fluid is suddenly blocked and can’t flow out of the eye. This causes a quick, severe rise in eye pressure.
- The sudden increase in pressure causes eye pain.
- Closed-angle glaucoma is an emergency.
- If you have had acute glaucoma in one eye, you are at risk for it in the second eye. Your doctor is likely to treat your second eye to try prevent another attack.
Secondary glaucoma occurs due to a known cause. Both open- and closed-angle glaucoma can be secondary when caused by something known. Causes include:
- Drugs such as corticosteroids
- Eye drops that dilate your eyes
- Eye diseases such as uveitis (an infection of the middle layer of the eye)
- Diseases such as diabetes
- Eye injury
Congenital glaucoma occurs in babies.
- It often runs in families.
- It is present at birth.
- It is caused when the eye does not develop normally.
- Most people have no symptoms
- Once vision loss occurs, the damage is already severe
- Slow loss of side (peripheral) vision (also called tunnel vision)
- Advanced glaucoma can lead to blindness
Symptoms may come and go at first, or steadily become worse. You may notice:
- 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
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
- Symptoms are usually related to the underlying problem causing the glaucoma
- Depending on the cause, symptoms may either be like open-angle glaucoma or angle-closure glaucoma
Exams and Tests
The only way to diagnose glaucoma is by having a complete eye exam.
- Usually you’ll be given eye drops to widen (dilate) your pupil.
- When your pupil is dilated, your eye doctor will look at the inside of your eye and the optic nerve.
- You may be given a test to check your eye pressure. This is called tonometry.
Eye pressure is different at different times of the day. Eye pressure can even be normal in some people with glaucoma. So your doctor will need to run other tests to confirm glaucoma. They may include:
- Using a special lens to look at the angle of the eye (gonioscopy)
- Photographs or laser scanning images of the inside of your eye (optic nerve imaging)
- Checking your retina. The retina is the light sensitive tissue at the back of your eye.
- Checking how your pupil responds to light (pupillary reflex response)
- 3-D view of your eye (slit lamp examination)
- Testing the clearness of your vision (visual acuity)
- Testing your field of vision (visual field measurement)
The goal of treatment is to reduce your 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 with eye drops.
- Most of the eye drops used today have fewer side effects than those used in the past.
- You also may be given pills to lower pressure in the eye.
If drops alone don’t work, you may need other treatment:
- Laser treatment uses a painless laser to open the channels where fluid flows out.
- If drops and laser treatment don’t work, you may need surgery. You will be put asleep with general anesthesia. The doctor will use a small knife to cut open a new channel so fluid can escape. This will help lower your pressure.
ACUTE ANGLE GLAUCOMA
An acute angle-closure attack is a medical emergency. You can become blind in a few days if you aren’t treated.
- You may be given drops, pills, and medicine given through a vein (by IV) to lower your eye pressure.
- Some people also need an emergency operation, called an iridotomy. The doctor uses a laser to open a new channel in the iris. Sometimes this is done with surgery. The new channel relieves the attack and will prevent another attack.
- To help prevent an attack in the other eye, the procedure will often be performed on the other eye. This may be done even if it has never had an attack.
- Congenital glaucoma is almost always treated with surgery.
- This is done using general anesthesia. This means the child is asleep and feels no pain.
If you have secondary glaucoma, treating the cause may help your symptoms go away. Other treatments also may be needed.
Open-angle glaucoma can’t be cured. You can manage it and keep your sight by following your doctor’s directions.
Closed-angle 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 you do with secondary glaucoma depends on what is causing the condition.
When to Contact a Medical Professional
If you have severe eye pain or a sudden loss of vision, get immediate medical help. These may be signs of closed-angle glaucoma.
You can’t prevent open-angle glaucoma. Most people have no symptoms. But you can help prevent vision loss.
- A complete eye exam can help find open-angle glaucoma early, when it is easier to treat.
- All adults should have a complete eye exam by the age of 40.
- If you are at risk for glaucoma, you should have a complete eye exam sooner than age 40.
- You should have regular eye exams as recommended by your doctor.
If you are at risk for closed-angle glaucoma, your doctor may recommend treatment before you have an attack to help prevent eye damage and vision loss.
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
Anderson DR. The Optic Nerve in Glaucoma. In: Tasman W, Jaeger EA, eds. Duane’s Ophthalmology. 2013 ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2013:vol 3, chap 48.
Kwon YK, Caprioli J. Primary Open-Angle Glaucoma. In: Tasman W, Jaeger EA, eds. Duane’s Ophthalmology.2013 ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2013:vol 3, chap 52.
Giaconi JA, Law SK, Caprioli J. Primary Angle-Closure Glaucoma. In: Tasman W, Jaeger EA, eds. Duane’s Ophthalmology. 2013 ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2013:vol 3, chap 53.
Mandelcorn E, Gupta N. Lens-Related Glaucomas. In: Tasman W, Jaeger EA, eds. Duane’s Ophthalmology.2013 ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2013:vol 3, chap 54A.
Updated by: Franklin W. Lusby, MD, Ophthalmologist, Lusby Vision Institute, La Jolla, California. Also reviewed by David Zieve, MD, MHA, Bethanne Black, and the A.D.A.M. Editorial team.
Source: From the National Institutes of Health, “Glaucoma” http://www.nlm.nih.gov website. Accessed December 2, 2015. http://www.nlm.nih.gov/medlineplus/ency/article/001620.htm
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