Glaucoma is the second most common cause of blindness. 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 glaucoma, 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 cannot 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 cannot flow out of the eye. This causes a quick, severe rise in eye pressure.
- Dilating eye drops and certain medicines may trigger an acute glaucoma attack.
- 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 health care provider is likely to treat your second eye to prevent a first attack in that eye.
Secondary glaucoma occurs due to a known cause. Both open- and closed-angle glaucoma can be secondary when caused by something known. Causes include:
- Medicines such as corticosteroids
- Eye diseases, such as uveitis (an inflammation 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.