What Causes Glaucoma?

Eye disease simulation, glaucoma - blurring view of two young boys

National Eye Institute, National Institutes of Health [Public domain], via Wikimedia Commons

Glaucoma is a group of eye conditions that damage the optic nerve, which is vital to good vision. This damage is often caused by abnormally high pressure in your eye. 

Glaucoma is one of the leading causes of blindness in the United States. It can occur at any age but is more common in older adults.

The most common form of glaucoma has no warning signs. The effect is so gradual that you may not notice a change in vision until the condition is at an advanced stage.

Vision loss due to glaucoma can't be recovered. So it's important to have regular eye exams that include measurements of your eye pressure. If glaucoma is recognized early, vision loss can be slowed or prevented. If you have the condition, you'll generally need treatment for the rest of your life.


Your eye is filled with a clear fluid which your body is continuously replacing. More fluid enters the eye in the back and the excess fluid drains through the front. As you age, the "drains" for the fluid become narrow and the eye cannot drain the excess fluid quickly enough. This fluid builds up and pressure increases in the eye. If the pressure gets high enough, it can damage the optic nerve because the pressure restricts the flow of blood to the nerve. This can cause vision loss and even blindness.


The signs and symptoms of glaucoma vary depending on the type and stage of your condition. For example:

Open-angle glaucoma

  • Patchy blind spots in your side (peripheral) or central vision, frequently in both eyes
  • Tunnel vision in the advanced stages

Acute angle-closure glaucoma

  • Severe headache
  • Eye pain
  • Nausea and vomiting
  • Blurred vision
  • Halos around lights
  • Eye redness

If left untreated, glaucoma will eventually cause blindness. Even with treatment, about 15 percent of people with glaucoma become blind in at least one eye within 20 years.

Risk Factors

Glaucoma seems to run in families. If a close relative has had glaucoma, you are at higher risk for the condition. People of African heritage are also at high risk for glaucoma.

Additional risk factors include:

  • Having high internal eye pressure (intraocular pressure)
  • Being over age 60
  • Having certain medical conditions, such as diabetes, heart disease, high blood pressure, and sickle cell anemia
  • Having certain eye conditions, such as nearsightedness
  • Having had an eye injury or certain types of eye surgery
  • Early estrogen deficiency, such as can occur after removal of both ovaries (bilateral oophorectomy) before age 43
  • Taking corticosteroid medications, especially eyedrops, for a long time


For most cases of age-related glaucoma, prescription eye drops can relieve the pressure in the eye, preventing further damage. These eye drops do not "cure" glaucoma, but will usually prevent any loss of vision due to the condition.


Early detection is critical to preventing glaucoma. People older than 40 should see an eye doctor at least every five years. Diabetics should visit an eye doctor yearly and people with elevated risk factors for glaucoma should also have more frequent appointments with an eye doctor.

Was this page helpful?

Article Sources

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial policy to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  • Mayo Clinic. Glaucoma

  • ADAM Medical Encyclopedia. Glaucoma