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Glaucoma is the leading cause of irreversible vision loss in Canada. Glaucoma is a group of eye diseases that cause vision loss by damaging the optic nerve which sends light information from the eye to the brain. Glaucoma is usually related to increased eye pressure. There is no cure for glaucoma, but early detection and treatment can help prevent damage to the optic nerve and vision loss.


Our eyes are filled with fluid. In the front part of the eye there is a clear liquid called aqueous humor. This liquid keeps the eye inflated and provides nutrition to the front of the eye. In a healthy eye, aqueous humor is constantly being produced and this new incoming fluid is balanced by an equal amount of fluid leaving the eye. Through this process, pressure in the eye is kept stable.

However, if there is a problem with how fluid drains, build up of fluid can cause high eye pressure, also called intraocular pressure or IOP. High eye pressure can cause damage to the optic nerve and vision loss. The optic nerve is made of tiny nerve fibers that send visual signals from the retina to the brain. If these fibers are damaged, light signals are disrupted causing “blind spots” in vision.


There are several types of glaucoma. Each type affects the eye in slightly different ways.

open-angle glaucoma

Open-angle is the most common form, affecting about 90% of people with glaucoma.[1] In open-angle glaucoma, the fluid in the eye does not drain as it should causing an increase in eye pressure. As pressure increases, it damages the optic nerve and creates blind spots in peripheral (side) vision. Because these blind spots are on the edge of vision and the process is painless, there are often no early warning signs or symptoms of open angle glaucoma. Some people are only diagnosed with glaucoma after a lot of vision loss has already occurred. It is essential to have regular eye exams so that your doctor can conduct the appropriate tests that will detect glaucoma early and start treatment.

angle closure glaucoma

Angle-closure glaucoma is less common and is typically a medical emergency. Also known as acute, or narrow-angle glaucoma, this happens when there is a sudden blockage that prevents fluid from leaving the eye. This build-up of fluid creates a rapid, dramatic increase in eye pressure. Symptoms of angle-closure glaucoma include severe headache, eye pain, nausea and vomiting, blurred vision and halos and redness. If left untreated, this can lead to sudden and irreversible vision loss. If you experience these symptoms, it is important to get checked immediately. If treated quickly, the eye can recover without long-lasting damage.

normal-tension glaucoma

In normal-tension glaucoma there is damage to the optic nerve even though eye pressure is within the normal range. The cause of this type of glaucoma is currently unknown. Scientists speculate that it could be due to variations in individuals’ optic nerve structure, or because there is not enough blood flow to the optic nerve.

congenital glaucoma

Congenital glaucoma affects children and is usually diagnosed between 3-6 months of age. Children with congenital glaucoma have difficulty clearing fluid out of their eyes which results in an increase in eye pressure.

Sometimes congenital glaucoma is inherited and other times it is not. If it is found and treated early, most cases will not cause permanent vision loss. Symptoms can include enlarged or cloudy eyes, watering, redness, and painful sensitivity to light.

pigmentary glaucoma

In pigmentary glaucoma, small pieces of pigment, or the colour of the eye, can rub off and cause deposits to form. In some people, these bits of pigment clog the drainage system of the eye, causing eye pressure to rise. If this results in damage to the optic nerve it becomes pigmentary glaucoma. This condition is more common in people ages 20-40 years, males and people who are nearsighted. Sometimes vigorous exercise can cause more pigment to be released in the eye, so it is important to discuss any exercise regime with your doctor if you have pigmentary glaucoma. In early stages of the disease there may be no symptoms. More advanced forms of pigmentary glaucoma can cause difficulty with side vision, blurry vision or halos.

secondary glaucoma

Secondary glaucoma is the name given to glaucoma that happens as a side effect to another medical condition or eye trauma. Some examples of causes of secondary glaucoma include eye injury, certain drugs including steroids, inflammation, or advanced cataracts of diabetes. While the causes may vary, the increase in eye pressure and optic nerve damage that occurs in secondary glaucoma is similar to the forms described above. Treatment options depend on the underlying cause.

risk factors

Anyone can develop glaucoma but there are several factors that can increase your risk of developing the disease, including:

  • high eye or intraocular pressure (IOP)
  • high blood pressure
  • family history of glaucoma
  • corneal thickness
  • being over the age of 55
  • previous eye injuries
  • long-term use of steroids
  • African, Asian, or Hispanic ancestry
  • nearsightedness
  • diabetes


Glaucoma can develop in one or both eyes, and in most forms of the disease there are no noticeable early symptoms. It is essential to have regular eye exams so that your doctor can conduct the appropriate tests that will detect glaucoma before vision loss occurs. If you experience any of these symptoms, please visit your eye doctor:

  • Loss of peripheral (side) vision
  • Halos around lights
  • Eye pain and/or redness
  • Blurred or decreased vision
  • Eye pain

Your ophthalmologist can conduct several tests to determine if you have glaucoma. These tests may include:

  • A visual acuity test to measure your ability to see from different distances
  • A visual field test to measure your peripheral vision
  • Dilated eye exams to look for damage to the optic nerve
  • Ocular tonometry to measure the intraocular pressure inside your eye
  • Pachymetry to measure corneal thickness


Currently there is no cure for glaucoma, and vision loss that results from optic nerve damage is permanent. This is why early diagnosis and treatment is so important. There are several treatments available to help lower eye pressure and hopefully prevent further vision loss. Your eye doctor will determine which type(s) of treatment may be right for you depending on the severity of your glaucoma.

eye drops

Eye drops are the most common early treatment for glaucoma. It is essential that these medications are taken regularly for them to help manage eye pressure. Depending on your individual condition you may need to take more than one eye drop. Be sure to follow the instructions for taking drops, including waiting at least five minutes between different medicines. Below is a list of commonly prescribed classes of drops. [2]

  • Prostaglandins: These drops reduce eye pressure by helping fluid drain out of the eye. Side effects can include mild eye irritation, a change of eye colour and longer eyelashes.
  • Beta blockers: These drops reduce the amount of fluid made by the eye. Side effects can include slowed heart rate, low blood pressure, challenges with breathing and tiredness.
  • Alpha-adrenergic agonists: These drops reduce the amount of fluid moving through the eye and help fluid move out of the eye. Side effects can include irregular heart rate, high blood pressure, red or itchy eyes, dry mouth and tiredness. These medications are typically used two or three times a day.
  • Carbonic anhydrase inhibitors: These drops reduce the amount of fluid made by the eye. Side effects can include metallic taste, frequent urination, and tingling in fingers and toes. These medications are typically used two or three times a day.
  • Rho kinase inhibitors: These drops reduce the amount of fluid made by the eye. Side effects may include eye redness and discomfort.
  • Miotic or cholinergic agents: These drops help fluid drain out of the eye. Side effects can include head and eye pain and possible vision changes. This medication may be used up to four times a day. This medication is no longer a common treatment because of the side effects and how frequently it has to be used every day.

oral medications

Sometimes drops will not be enough to keep eye pressure in check. Your doctor may also prescribe an oral medication, typically a carbonic anhydrase inhibitor to help reduce pressure.

laser surgery

Laser treatment can help some people with glaucoma. The most common form of this treatment is called laser trabeculoplasty. For this procedure, you will first be given numbing drops and then a laser will be aimed at your eye using a special lens. The laser will help open the drainage path and help fluid move out of the eye. This procedure is usually painless and can be done in your doctor’s office. You can return to normal activities the day after the procedure. Laser treatment is effective for most people, but it may take 4-6 weeks to see if the treatment was successful. Even with laser surgery you will likely need to continue using eye drops. It is also important to regularly visit your eye doctor to monitor eye pressure. Some people will require laser surgery more than once.

conventional surgery

In addition to laser surgery, there are other more conventional surgical techniques that can be used to treat glaucoma. Commonly called trabeculectomy, this procedure is done in the operating room. The surgeon cuts a small flap in the white part of the eye called the sclera. Next, they will create a path that will allow fluid to drain out of the eye in order to lower eye pressure. These surgeries can have side effects and are usually only used if other treatments have failed.

minimally invasive glaucoma surgeries (MIGS)

MIGS are a group of devices and procedures that aim to lower interocular pressure by improving fluid drainage or reducing the amount of fluid produced by the eye. They are starting to be used more widely in Canada. Many MIGS show promise in treating certain types of glaucoma, including some where conventional surgery would not be a good option. Because these procedures are less invasive recovery is usually quicker than after conventional surgeries. However, the current evidence shows that MIGS are not always better than other treatment options. Speak to your doctor to find out what treatment options are best for you.


Many research groups are working to develop treatments and cures for glaucoma. These treatments include medications, optic nerve regeneration and gene-targeting.  

  • Medications: many types of medicines are being investigated for use with glaucoma. Some examples of current research include looking at the protective role of some vitamins, investigating ways to reduce pressure even further with medication and developing slow-release drugs that would need to be used less often.
  • Optic nerve regeneration: There are several research groups that are looking into how cell-based therapies, like stem cells, may be used to help treat vision loss from glaucoma. Work is ongoing in this area, and in the future stem cells may be used to protect the optic nerve or restore vision that has been lost in glaucoma. These approaches are still at early stages of research and are not ready to test in human clinical trials.
  • Gene targeting: Researchers are also looking at ways to replace mutated genes that cause genetic forms of glaucoma. This work is being done in animal models and is not yet in human clinical trials.
  • Learn more about three glaucoma projects Fighting Blindness Canada is funding.


Fighting Blindness Canada has developed resources to help you navigate vision care. Follow the links below to learn more.

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Updated on March 21, 2024

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