What you should know about: Glaucoma

Glaucoma is an eye disease in which the optic nerve – the connection between the eye and brain – gradually atrophies, which means fibres there die. It’s called “the silent thief of sight” because irreversible damage can occur before there are noticeable symptoms. One of the most common causes of blindness worldwide, glaucoma usually affects both eyes, though it can be worse in one eye than the other.  

By far the most common type of glaucoma is open-angle glaucoma, which means the mesh-like drainage structures where the fluid in the eye drains appear open, but the fluid is draining too slowly, or because the eye is producing fluid faster than it can be drained. This type of glaucoma usually progresses slowly. 

Angle-closure glaucoma, also called closed-angle glaucoma, occurs when the eye’s drainage system becomes fully or near-fully blocked. If this happens suddenly, it’s called acute angle-closure glaucoma and is a medical emergency. Intermittent or chronic angle-closure glaucoma, where the eye’s drainage system regularly becomes partially blocked for short or long periods, needs prompt attention but isn’t an emergency.

A major risk factor for glaucoma is high intraocular pressure – the pressure inside the eye is too high. This puts pressure on the optic nerve. The fluid in the eye, called aqueous humour, is constantly being created and drained from structures at the front of the eye. If the drainage system isn’t working well, or if the eye is creating too much aqueous humour, pressure builds up.

In some patients, however, intraocular pressure is within the normal range. This is called low-tension or normal-tension glaucoma, and it’s quite common. In these patients, even the normal pressure in the eye may cause damage to the optic nerve.

There are rarer types of glaucoma, including a type called pigmentary glaucoma, where exercise can bring on symptoms such as eye pain, red eyes and blurry vision. Glaucoma can also be congenital – usually diagnosed in infancy – or caused by other medical conditions, in which case it’s called secondary glaucoma.   

Glaucoma is more common in older people, though it can occur at any age. Diabetes and being hit in the eye are among the conditions that can cause secondary glaucoma in some patients.

You are at higher risk of glaucoma if you have a family history of it; if you have thin corneas; if you’re very nearsighted or farsighted; or if you’ve had an eye injury or certain types of eye surgery. Other risk factors may include being of Asian, Black, Latin American or Inuit heritage; being prone to migraines or Raynaud’s syndrome; and often feeling cold.

Glaucoma typically doesn’t cause any symptoms in the early stages. That’s why it’s so important to have regular eye exams. This is even more important if you have any risk factors for glaucoma. 

In later stages, symptoms may include a loss of peripheral vision, progressing to blind spots or blurriness in more central vision.

If any of the following symptoms come on suddenly, you may have acute angle-closure glaucoma: 

• Sudden, severe eye pain 
• Red eyes 
• Blurry or hazy vision 
• Seeing halos around lights 
• Severe headache 
• Nausea or vomiting

If you have the sudden onset of symptoms such as these, even if you don’t have all of them, call your optometrist or ophthalmologist and ask to be seen right away. While these symptoms may have other causes, most of them more common and less serious, in the event you do have acute angle-closure glaucoma, a delay in treatment could result in vision loss.  

If you don’t have an optometrist or ophthalmologist, or they’re not available, and you’re in or near Waterloo, call the Waterloo Eye Institute Urgent Care Clinic at 519-888-4623. You don’t need to be an existing patient. An on-call optometrist is available for certain hours outside regular clinic times – for more information, see Urgent and After-Hours Care or call 519-888-4567, ext. 40600. If acute symptoms start outside on-call hours, go to the nearest emergency room.

Symptoms of intermittent or chronic angle-closure glaucoma may include transient eye pain or discomfort, especially in low light, and seeing coloured halos around lights at night. Symptoms such as these mean you should make an appointment with an optometrist as soon as reasonably possible.

Glaucoma diagnosis can be tricky because some possible indications of glaucoma might be an individual patient’s normal state. It’s therefore common for people to be identified as glaucoma suspects before they’re diagnosed as having glaucoma. 

If you’re a glaucoma suspect, your optometrist will ask for a detailed medical history and repeat a series of tests a few times over the course of a year. You will have your eye pressure and corneal thickness measured and peripheral vision tested. Your optometrist will also examine the drainage system at the front of the eye, your optic nerve and the fibres around the optic nerve. Repeating these tests will indicate if your eyes are changing, and if so, how fast.  

The bad news is that damage caused by glaucoma can’t be reversed. The good news is that with regular eye exams, glaucoma can be treated early, preventing vision loss. Even if some vision loss has already occurred, treatment can slow down or stop disease progression. 

Treatment will depend on the type of glaucoma you have but usually involves medicated eye drops that lower your eye pressure. You may be prescribed more than one eye drop and/or oral medications. It’s important to take all medications as directed to preserve your vision. Discuss any side effects with your optometrist or ophthalmologist. 

Some patients opt for laser surgery to help the eye’s drainage system work better. For many but not all patients, this may mean they no longer need eye drops. Laser surgery is highly effective and has minimal side effects beyond the initial healing period. However, it may need to be repeated every five years or so. In Ontario, laser surgery is done by ophthalmologists. In some jurisdictions, an optometrist might perform the laser surgery.  

In some cases, incisional surgery is necessary to improve drainage, implant a drainage tube or treat cataracts, which can lower pressure in addition to replacing a cloudy lens with a clear artificial lens. An ophthalmologist will perform these surgeries. Whether you’re getting laser or incisional surgery, if you’re a patient of the Waterloo Eye Institute, we can coordinate care with your ophthalmologist. 

If you have acute angle-closure glaucoma, you will be given medication, usually in the form of eye drops, to quickly bring down your eye pressure. You will then need laser surgery.

At the Waterloo Eye Institute, if you’re a glaucoma suspect, you will typically be asked to repeat diagnostic tests every four months for a year. These may seem time consuming and repetitive but are necessary to establish what is normal for you and if glaucoma is causing changes. 

If you’re only suspected of having glaucoma, your eye exams are not covered under the Ontario Health Insurance Plan (OHIP) if you’re under 65. If you’re 65 or over, two exams a year are covered. A full eye exam costs $120 (all fees listed are as of January 2024 and are subject to change) and includes eye pressure testing and examination of the drainage system at the front of the eye. 

There are additional fees for tests not included in standard eye exams. A visual field test costs $60 and needs to be repeated three times a year for a glaucoma suspect. Optical coherence tomography (OCT) imaging of the back of your eye, which can detect changes to the optic nerve, is needed twice a year and costs $75 each time. Your optometrist will also take a picture of the back of your eye, which is needed once a year and costs $25. Some private insurance or benefit plans may cover these fees. 

If you are diagnosed with glaucoma, OHIP will cover visual field testing and two eye exams a year regardless of age. However, we recommend most patients be examined three times a year in perpetuity, though some patients with slow-progressing glaucoma can do with twice a year, while others with more severe forms may need to be seen four times a year – more if there is a sudden change. 

Glaucoma medications, including eye drops, are mostly covered under OHIP, but it’s possible your optometrist may recommend a medication that isn’t covered. Most glaucoma patients need at least one eye drop a day; some need more. If you need glaucoma surgery, this is covered under OHIP. 

Make an appointment at the Waterloo Eye Institute 

The University of Waterloo School of Optometry and Vision Science is ranked fifth worldwide in research output for schools of optometry. Our researchers have studied ocular blood flow and the visual field of glaucoma patients and have contributed to advancing the use of OCT imaging for glaucoma.  

Current areas of research at the School include improving adherence to glaucoma treatment using digital tools and improving ways to deliver drugs to the eye. Methods under investigation include drug delivery through contact lenses and drugs that bind to gel-like proteins on the eye surface so drugs can stay on the eye longer and therefore work better at lower concentrations. 

Interested in participating in research? Check out our current studies recruiting participants. The Centre for Ocular Research and Education, which is part of the School, also regularly recruits participants for ocular surface and contact lens research.