Glaucoma is an eye disease that can damage optic nerve tissue and result in vision loss. Depending on the type, treatment may involve medications or surgery.

The optic nerve supplies visual information to your brain from your eyes.

Glaucoma is usually, but not always, the result of abnormally high pressure inside the eye. Over time, the increased pressure can erode optic nerve tissue, leading to vision loss or even blindness.

If it’s caught early, you may be able to prevent additional vision loss.

Many people with glaucoma, especially those with earlier stages of this eye disease, may not experience any symptoms and not recognize they have glaucoma.

This is true for the most common glaucoma type, open-angle glaucoma. There are no symptoms except for gradual vision loss.

As this type of glaucoma gets worse, it can lead to increased eye pressure and tunnel vision, or loss of peripheral side vision.

Regular comprehensive eye exams with an ophthalmologist or other licensed eye specialist is important for your eye health, to monitor any changes in your vision that may be related to glaucoma.

The back of your eye continuously makes a clear fluid called aqueous humor. As this fluid is made, it fills the front part of your eye. Then, it leaves your eye through channels in between your cornea and iris.

If these channels are blocked or partially obstructed, the natural pressure increases in your eye (known as intraocular pressure, or IOP).

As your IOP increases, your optic nerve may become damaged. As damage to your nerve progresses, you may begin losing sight in your eye.

Eye doctors believe one or more of these factors may contribute to IOP increases:

  • blocked or restricted drainage in your eye
  • medications, such as corticosteroids
  • poor or reduced blood flow to your optic nerve
  • high or elevated blood pressure

Learn more about eye pressure behind the eye and what can cause this sometimes-painful feeling.

Five major types of glaucoma exist.

1. Open-angle (chronic) glaucoma

Primary open-angle glaucoma is the most common type, with no symptoms before gradual vision loss.

With open-angle glaucoma, the water-like fluid produced in the tissue of your eye near the cornea (aqueous humor) doesn’t drain adequately, leading to a gradual eye pressure increase. This pressure damages the optic nerve and leads to vision loss.

That vision loss may be so slow that you may not experience any other symptoms or signs of this damage, before that damage becomes permanent and vision loss cannot be restored.

2. Angle-closure (acute) glaucoma

If the flow of your aqueous humor fluid is suddenly blocked, the rapid buildup of fluid may cause a severe, quick, and painful increase in pressure.

This is known as angle-closure glaucoma. It’s considered an emergency situation, requiring immediate medical attention for any symptoms that might include:

  • severe eye pain
  • headache
  • nausea and vomiting
  • redness in your eye
  • blurred vision
  • rainbow-colored halos

3. Congenital glaucoma

Congenital glaucoma can be hereditary. Children born with congenital glaucoma have a defect in the angle of their eye, which slows or prevents normal fluid drainage.

Congenital glaucoma usually includes symptoms, such as cloudy eyes, excessive tearing, or sensitivity to light.

4. Secondary glaucoma

Secondary glaucoma is often a side effect of injury or another eye condition, such as cataracts or eye tumors.

Medicines, such as corticosteroids, may also cause this type of glaucoma.

Rarely, complications from eye surgery can cause secondary glaucoma.

5. Normal-tension glaucoma

In some cases, people without increased eye pressure can develop damage to their optic nerve. This is known as normal tension glaucoma.

Researchers believe that extreme sensitivity or a lack of blood flow to your optic nerve may be a factor in this type of glaucoma.

Glaucoma is the second leading cause of blindness around the world. The risk factors for glaucoma include:

  • Age: People over 60 face higher risk, which increases slightly each year. If you’re African American, your increase in risk begins at 40 years old.
  • Ethnicity: African Americans or people of African descent are significantly more likely to develop glaucoma than Caucasians. People of Asian descent are at a higher risk of angle-closure glaucoma, and people of Japanese descent have a higher risk of developing low-tension glaucoma.
  • Past eye health issues: Chronic eye inflammation and thin corneas can lead to increased eye pressure. Physical injury or trauma to the eye, such as being hit in the eye, can also increase eye pressure.
  • Family history: Some types of glaucoma may run in families. If your parent or grandparent had open-angle glaucoma, you’re at an increased risk of developing the condition.
  • Medical history: People with diabetes and those with high blood pressure and heart disease have an increased risk of developing glaucoma.
  • Certain medications: Using corticosteroids for extended periods may increase your risk of developing secondary glaucoma.

Your ophthalmologist will want to perform a comprehensive eye examination to diagnose glaucoma.

They’ll check for signs of deterioration, including loss of nerve tissue.

They may also use one or more of the following tests and procedures:

  • Symptoms and medical history: Your doctor will want to know if you’ve been experiencing any symptoms and any personal or family history of glaucoma. They’ll also ask for a general health assessment to determine if any other health conditions may impact your eye health.
  • Tonometry test: This class of tests measures your eye’s internal pressure.
  • Pachymetry test: People with thin corneas have an increased risk of developing glaucoma. A pachymetry test can tell your doctor if your corneas are thinner than average.
  • Perimetry test: Commonly known as a visual field exam, this test involves looking into a machine and, with one eye covered, clicking a button every time you see a flashing dot that appears somewhere on the visual field display. It helps your doctor determine whether glaucoma is affecting your vision by measuring your central and peripheral (side) vision.
  • Monitoring your optic nerve: If your doctor wants to monitor for gradual changes to your optic nerve, they may take photographs of it to compare it side-by-side over time.

Glaucoma treatment aims to reduce IOP to stop any additional eyesight loss.

Typically, your doctor will begin treatment with prescription eye drops.

If these don’t work or more advanced treatment is needed, your doctor may suggest one of the following treatments:

Medications: Several medications designed to reduce IOP are available. These are available in pill form or eye drops, but the drops are more common. Your doctor may prescribe one or a combination of these.

Lasers: Your eye doctor may use laser treatment in the office to reduce eye pressure. That may be in the case of an emergency with angle-closure glaucoma, or to help pressure reduce slowly for open-angle glaucoma.

Surgery: If a blocked or slow channel is causing increased IOP, your doctor may suggest surgery to create a drainage path for fluid or destroy tissues responsible for the increased fluid.

Angle-closure glaucoma treatment

Treatment is different for this type of glaucoma, which is considered a medical emergency and requires immediate care to reduce eye pressure.

Your eye care team may first try medication to reverse the angle closure. If that’s not successful, they may perform a laser peripheral iridotomy (LPI). This procedure creates small holes in your iris to allow for increased fluid movement.

Researchers around the world continue studying glaucoma and different ways to treat this eye disease, ranging from laser procedures to other forms of surgery or treatment.

If you can lower the increased eye pressure to normal levels, vision loss may be slowed or even stopped.

However, because there’s no cure for glaucoma, you’ll likely need treatment for the rest of your life to regulate your eye pressure levels.

Glaucoma is centered on eye pressure and the damage it can cause. Any vision loss that’s already developed because of glaucoma is typically permanent.

That is why prevention is key for glaucoma and any resulting vision loss.

Glaucoma can’t be prevented, but it’s still important to catch it early so you can begin treatment that will help prevent it from getting worse.

An annual preventive eye care appointment is the best way to catch any type of glaucoma early, especially for those with a family history of glaucoma.

Make an appointment with an ophthalmologist. Simple tests performed during these routine eye checks may be able to detect damage from glaucoma before it advances and begins causing vision loss.