Glaucoma is an often painless but serious eye condition that causes damage to your optic nerve.

This nerve connects your eye to your brain, allowing the incoming visual information to be processed by the brain, which then identifies what you’re seeing.

The condition can cause blindness. Indeed, glaucoma is the second leading cause of blindness in the world.

Causes and Risk Factors of Glaucoma

Researchers don't fully understand how glaucoma occurs.

One known cause is the optic nerve becoming compressed because of high pressure within the eye. Another cause can be reduced blood flow within the optic nerve.

But even people with normal eye pressure can develop glaucoma. In addition to high eye pressure, high blood pressure can also lead to optic nerve damage.

Unfortunately, glaucoma has no obvious warning signs and causes no pain. Once damage to your eyesight has occurred, it cannot be reversed.

With an early diagnosis, there are treatments available that can slow the progression of the disease and prevent vision loss.

The top risk factor for glaucoma is having high pressure within your eye.

Other important risk factors include:

  • Age; being 40 or older
  • African, Hispanic, or Asian heritage
  • Thin corneas (the clear layer at the front of the eye)
  • Family history of glaucoma
  • Farsightedness or nearsightedness
  • Previous eye injuries
  • Steroid medication use
  • Certain conditions, such as diabetes, migraines, hypertension, or poor blood circulation.
People with more than one of these factors are at a higher risk of developing glaucoma.

What Is Intraocular Pressure?

Within healthy eyes, there's a clear fluid called aqueous humor that circulates to nourish the eye and its various parts. This fluid normally drains out of the eye.

When drainage is slowed, pressure within the eye (called intraocular pressure) can build up and harm the optic nerve by compressing it.

The optic nerve is vital to your ability to see. It carries signals from the retina in the eye to the brain.

When the optic nerve's fibers are damaged, blind spots can develop in your field of vision.

Types of Glaucoma

There are several different kinds of glaucoma. They include:

Open-Angle Glaucoma

This is the most common form of glaucoma.

It occurs when the eye's fluid passes too slowly through the open drainage “angle” where the eye's cornea and iris meet.

The first sign of a problem with this type of glaucoma is usually the loss of your peripheral (side) vision.

You may compensate, without knowing it, by turning your head to the side to see things. You may not realize you're losing your vision until the loss is severe.

Low-Tension or Normal-Tension Glaucoma

In this form of glaucoma, optic nerve damage occurs even though your eye pressure is not very high. It’s unclear why the damage occurs.

Angle-Closure Glaucoma

Formerly called narrow-angle glaucoma, this urgent medical emergency occurs when the drainage angle closes because it's blocked by part of the iris.

Eye pressure builds suddenly when fluid can't drain from your eye.

With this type of glaucoma, you'll experience severe pain and nausea. Your eye will redden and your vision will blur.

It's very important to seek emergency treatment immediately at a hospital or clinic. Without treatment, you could lose sight in the affected eye.

In most cases, laser surgery and drugs can clear the blockage, lower the eye's pressure, and restore vision.

Congenital (Childhood) Glaucoma

Babies can be born with a defective angle in the eye that doesn't allow fluid to drain properly.

The symptoms of congenital glaucoma are usually quite noticeable.

Children with the condition may have a cloudy eye, be very sensitive to light, or produce an excess of tears.

Your child's doctor will likely recommend a surgical procedure to correct the problem.

The procedure is considered safe and effective. When done early in life, it offers children an excellent chance of having good vision.

Other types of glaucoma include:

Pigmentary Glaucoma

This relatively rare type of glaucoma is a complication of a condition known as pigment dispersion syndrome. It occurs when pigment granules at the back of the iris flake off into the fluid in the eye. If they clog the eye’s drainage canals, it can lead to increased eye pressure and optic nerve damage. About 30 percent of cases of pigment dispersion syndrome lead to pigmentary glaucoma.

Traumatic Glaucoma

Injury to the eye that may be caused by blunt trauma to the head or flying debris can lead to glaucoma.

When bleeding in the eye occurs, the eye’s drainage system can become clogged and lead to increased eye pressure.

Traumatic glaucoma most commonly occurs when the ciliary body, which produces eye fluid, is torn.

Irido Corneal Endothelial Syndrome (ICE)

ICE occurs when cells on the back of the cornea spread over drainage tissue in the eye. This leads to blockage of the drainage canals and eye pressure buildup.

Uveitic Glaucoma

Uveitis is an inflammation of the uvea, or the middle layer of the eye that’s located under the white of the eye. The inflammation can obstruct fluid outflow from the eye. Up to 20 percent of uveitis patients develop glaucoma.

Duration of Glaucoma

If a person develops glaucoma, they will have it for the rest of their lives. Timely diagnoses and treatment can prevent loss of vision.

Even after glaucoma is treated with medicine or by surgery, the patient will need to be followed for the rest of their lives, says Singh. “That is to make sure they don’t get another form of glaucoma or in case their treatment was not enough, and they now need some additional medical therapy to keep that pressure under control,” she says.

Complications of Glaucoma

If glaucoma goes untreated it can cause significant vision loss that can’t be restored. If it goes untreated long enough, it can lead to vision loss in both eyes and may even lead to blindness.
Blindness as a result of glaucoma is a rare occurrence, says Singh. It happens in about 5 percent of people who are diagnosed with glaucoma.
As with any surgery, there can be risks from glaucoma surgery. These complications can include vision loss that doesn’t go away, bleeding, infection, low eye pressure, scarring, and cataract formation.

Black Americans, Hispanic Americans, and Glaucoma

Black Americans and Glaucoma

Glaucoma occurs about five times more often in Black Americans than in other groups, and blindness from the disease is six times more common. There are many factors that contribute to this disparity, says Singh.

“Genetics appears to have a role as well as things such as access to healthcare or lack of insurance,” she says.

Private health insurance appears to play a large part in glaucoma testing, which is necessary for timely diagnosis and treatment. A study published in Ophthalmology found that Black Americans with Medicaid insurance had a 291 percent higher chance of not receiving any glaucoma testing compared with those with private health insurance.
The authors concluded that disparities in testing were observed for people with Medicaid insurance versus commercial insurance across all races and ethnicities but were most notable for Black Americans.
According to U.S. Census estimates from 2018, the uninsured rate was 17.8 percent among Hispanic Americans and 9.7 percent for Black Americans, compared with 5.4 percent among white Americans. The percentage of people who had private insurance was 49.6 percent for Hispanics, 55.4 percent for Black Americans, and 74.8 percent for white Americans.

Hispanic Americans and Glaucoma

The Los Angeles Latino Eye Study (LALES) reported an overall prevalence of open-angle glaucoma among Hispanics at nearly 5 percent — similar to what has been reported for Black Americans.
It’s estimated by that 2050, half the people living in the United States with glaucoma will be Hispanic or Latino. Lack of access to healthcare and health insurance is a big part of the issue. Hispanic Americans are less likely to have had an eye exam or have access to eye health and eye care services, according to the CDC.

Resources We Love

American Academy of Ophthalmology

The mission of the American Academy of Ophthalmology is to protect sight and empower lives by advocating for patients, as well as educating the public and eye health professionals.

Glaucoma Research Foundation

This national nonprofit organization is dedicated to finding a cure for glaucoma. It provides information, tips on eye care, and updates on the latest research.

American Glaucoma Society

This professional organization provides clinical and scientific evidence for both patients and healthcare professionals. A patient portal contains resources on finding an eye doctor, education on glaucoma and answers to FAQs.

National Eye Institute

The National Eye Institute was established by congress over 50 years ago to protect and prolong the vision of the American people. This organization provides education and funds research in eye health.

Additional reporting by Becky Upham.

Editorial Sources and Fact-Checking

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