Glaucoma is a condition in which fluid pressure rises within the eye. Without treatment, it can damage the optic nerve and lead to vision loss.

Glaucoma is relatively common. It is most likely to affect white people after the age of 60 and Black and Hispanic people after the age of 40.

The symptoms of the most common type — open-angle glaucoma — start slowly and are hard to notice. However, an ophthalmologist may detect changes during an eye test.

There is no cure for glaucoma, but treatment can slow or stop its progression.

This article will look at the causes, symptoms, and treatment of glaucoma. We will also explain the different types of glaucoma and possible surgical procedures.

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Dr. Charles J. Ball/Corbis Documentary/Getty Images

Glaucoma refers to a buildup of pressure within the eye that causes damage to the optic nerve.

The front part of the eye contains a clear fluid, the aqueous humor. This fluid nourishes the eye and gives it its shape. The eye constantly produces this fluid and drains it away through a drainage system.

If a person has glaucoma, the fluid drains too slowly out of the eye. When this happens, fluid builds up, and pressure inside the eye rises.

If a person does not manage this pressure, it may damage the optic nerve and other parts of the eye, leading to vision loss.

Glaucoma usually affects both eyes, although it may affect one eye more severely than the other.

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Experts do not know exactly what causes glaucoma, but some health conditions increase the risk.

If a person has primary glaucoma, there is no identifiable cause. If they have secondary glaucoma there is an underlying cause, such as a tumor, diabetes, hypothyroidism, an advanced cataract, or inflammation.

Risk factors for glaucoma include the following:

  • for white people, being over 60 years old
  • for Black and Hispanic people, being over 40 years old
  • having diabetes or another underlying health condition
  • a family history of glaucoma
  • having an eye injury or condition
  • previous eye surgery
  • severe myopia (nearsightedness)
  • taking corticosteroid medication, especially as eye drops
  • high blood pressure
  • genetic factors, which can lead to childhood glaucoma

There are several types of glaucoma, including:

  • open-angle glaucoma
  • closed-angle glaucoma
  • low-tension glaucoma
  • pigmentary glaucoma

Open-angle glaucoma

Also known as chronic glaucoma, this is the most common type. It develops slowly, and a person may not notice any symptoms, even if slight vision loss occurs.

Many people with this type of glaucoma do not seek medical help until permanent damage has already occurred.

Closed-angle glaucoma

This is also known as acute angle-closure glaucoma. It can start suddenly with pain and rapid vision loss.

As the symptoms are noticeable, the individual will usually seek medical help, resulting in prompt treatment. This can prevent permanent damage.

Low-tension glaucoma

This is a rarer form of glaucoma in which eye pressure is not higher than the normal range but still causes damage that affects the optic nerve.

Experts know little about this condition, but it might be due to reduced blood supply to the optic nerve.

Pigmentary glaucoma

This is a type of open-angle glaucoma that typically develops during early or middle adulthood.

It involves changes in the pigment cells that give color to the iris. In pigmentary glaucoma, the pigment cells disperse throughout the eye.

If the cells build up in the channels that drain fluid from the eye, they can upset the normal flow of fluids in the eye. This can lead to a rise in eye pressure.

Childhood glaucoma

In rare cases, glaucoma can affect children due to genetic factors. The child may have:

  • unusually large eyes
  • excessing tearing
  • cloudiness in the cornea
  • sensitivity to light

Medication and surgery can help prevent vision loss.

The symptoms of the two most common types of glaucoma are different.

Open-angle glaucoma

Symptoms develop slowly, and a person may not notice them until the later stages.

They include:

  • gradual loss of peripheral vision, usually in both eyes
  • tunnel vision

Closed-angle glaucoma

The symptoms of acute glaucoma appear suddenly and include:

  • eye pain, usually severe
  • blurred vision
  • nausea and possibly vomiting
  • seeing halo-like glows around lights
  • red eyes
  • sudden, unexpected vision problems, especially in poor lighting

Ophthalmologists regularly check for glaucoma as part of a routine eye test. They can use several diagnostic tests:

Opthalmoscopy

The eye doctor puts drops into the eye to widen the pupil, then examines the inside of the eye using a special light and magnifying glass.

Perimetry

The doctor carries out a visual field test to check the person’s peripheral (side) vision. The person looks straight ahead while the doctor presents a light spot in different places around the edge of their vision. This helps create a map of what the person can see.

Tonometry

After using eye drops to numb the eye, the doctor measures the pressure in the eye with a device that either touches the cornea (applanation) or uses a puff of air.

Gonioscopy

The doctor uses eye drops to numb the eyes, then places a type of contact lens on the eye. The lens has a mirror that that can show if the angle between the iris and the cornea is normal, too wide (open), or too narrow (closed).

Pachymetry

The doctor places a probe on the front of the eye to measure the thickness of the cornea. The doctor will take this into account when they assess all the results, as corneal thickness can affect eye pressure readings.

Treatment aims to improve the flow of fluid from the eye, reduce fluid production, or both.

There are several ways to do this:

Eye drops

Most people will use eye drops as initial treatment. These either reduce the amount of fluid the eye makes or improve drainage.

It is essential to follow a healthcare professional’s instructions carefully for the best results and to prevent adverse effects.

Examples of eye drops include:

  • prostaglandins
  • carbonic anhydrase inhibitors
  • cholinergic agents
  • beta blockers
  • nitric oxide releasers
  • rho kinase inhibitors

Adverse effects can include:

  • stinging
  • redness
  • change in eye color or skin around the eye
  • headaches
  • dry mouth
  • occasionally, retinal detachments or difficulty breathing

If the adverse effects persist, the doctor may change the dose or recommend a different option.

If drugs do not help, or if the person cannot tolerate them, a doctor may recommend surgery.

Surgery usually aims to reduce the pressure inside the eye. Possible interventions include:

  • Trabeculoplasty: The surgeon uses a laser beam to unblock clogged drainage canals, making it easier for fluid to drain out.
  • Filtering surgery: If laser surgery does not help, the surgeon may open channels in the eye to improve fluid drainage.
  • Drainage implant: This may help if glaucoma occurs in children or as a result of another health condition. The surgeon inserts a small silicone tube into the eye to improve drainage.

Treating acute angle-closure glaucoma

Acute angle-closure glaucoma is a medical emergency.

A doctor will give pressure-reducing medications immediately.

They may use a laser procedure to create a tiny hole in the iris, allowing fluids to pass into the eye’s drainage system. This procedure is called an iridotomy.

Even if glaucoma only affects one eye, the doctor may treat both, because there is a risk that it might occur in the other eye, too.

There is no known way to prevent glaucoma, but early diagnosis and treatment can improve the chance of preventing vision loss.

It is essential to have regular eye checks because this is the only way to detect glaucoma in the early stages. The Glaucoma Foundation recommend having a baseline test at the age of 40. The doctor will use the results to detect future changes.

A doctor can advise an individual on how often they should have an eye test, depending on their risk level.

Glaucoma is a common eye condition that affects people as they get older. It happens when fluid does not drain from the eye, increasing pressure and the risk of damage to the optic nerve.

It may have no symptoms in the early stages but can lead to vision loss. Regular eye tests can help detect changes that will enable a person to start treatment, usually with eye drops. This treatment can slow or prevent vision loss.