Glaucoma Screening and OCT Imaging in Montréal
Glaucoma is a disease that slowly damages the optic nerve, the cable that carries what the eye sees to the brain. It usually causes no pain and no symptoms until a large part of the vision is already gone, and the vision it takes does not come back. The only way to find it early is a regular eye exam. At PrimeVision, our optometrists screen for glaucoma using eye pressure measurement, OCT imaging and visual field testing, all in the clinic.
What glaucoma is
Glaucoma is not a single disease but a group of eye conditions that damage the optic nerve. The damage is often linked to pressure inside the eye that is too high for the nerve to tolerate. The front of the eye constantly makes a clear fluid, which then drains out. When the drainage does not keep up, pressure can rise and, over time, nerve fibres are lost. In its early stages, glaucoma usually causes no symptoms at all.
Open-angle glaucoma
This is the most common form. It develops slowly over years, usually in both eyes, and affects side vision first. Because the brain fills in the gaps and central vision stays clear for a long time, most people notice nothing until the damage is advanced.
Angle-closure glaucoma
This less common form happens when the drainage angle inside the eye becomes blocked. It can develop slowly, but it can also happen suddenly. A sudden attack can cause a painful red eye, blurred vision, halos around lights, headache, nausea or vomiting. That is an emergency: go to a hospital emergency room right away. Our page on urgent eye care explains which eye problems need the hospital.
Who is most at risk of glaucoma
- Adults over 40, with the risk rising every decade
- People with a parent, brother or sister who has glaucoma
- People with high eye pressure
- People who are very nearsighted
- People with diabetes
- People of African, Caribbean, Hispanic or Asian descent, depending on the type of glaucoma
- People who have used corticosteroids for a long time
Having one or more risk factors does not mean you will develop glaucoma, and some people with glaucoma have none. Tell your optometrist about your family history and about the medications you take, including any cortisone (corticosteroid) medication, whether drops, pills or another form.
How we screen for glaucoma
Eye pressure
We measure the pressure inside each eye. High pressure is the main risk factor for glaucoma, but it is not the whole story: some people develop glaucoma at normal pressure, and some people have high pressure without damage. That is why pressure alone is never enough.
Optic nerve examination
Your optometrist looks directly at the optic nerve at the back of the eye and notes its shape and colour, and compares it with previous visits.
OCT imaging
OCT, or optical coherence tomography, is a scan that uses light to measure the thickness of the nerve fibre layer around the optic nerve, in thousandths of a millimetre. It takes a few seconds, nothing touches the eye, and it can show thinning of the nerve before any vision is lost. OCT also images the macula, which helps detect macular degeneration and diabetic changes. Each scan is stored, so we can compare year over year and catch a slow change.
Visual field testing
A visual field test maps your side vision, where glaucoma does its first damage. You look at a central target and press a button each time you notice a small light. We use an Octopus 900 perimeter. The test takes a few minutes per eye and shows whether any area of your vision has become less sensitive.
What to expect during your visit
Glaucoma screening is done as part of your eye exam, and none of the tests hurt. For the eye pressure measurement, you may feel a brief puff of air, or your optometrist may put in a numbing drop before gently touching the surface of the eye with a measuring instrument. The OCT scan and the visual field test are done sitting at a machine while you look at a target.
Your optometrist may also use drops to widen (dilate) your pupils for a better view of the optic nerve and the retina. Your vision can then stay blurry and sensitive to light for a few hours, so bring sunglasses and consider arranging a ride home. If you wear contact lenses, bring your glasses and your lens case, as you may be asked to remove your lenses for some tests.
What happens if something is found
Most people who are flagged at screening do not have glaucoma. They are what we call glaucoma suspects, and they are followed more closely, with repeat measurements, so that a real change is caught early. If the findings point to glaucoma, or if you need treatment that goes beyond what an optometrist provides, we refer you to an ophthalmologist and send the results of your tests with the referral. We continue to follow you alongside your specialist.
How glaucoma is treated
Vision already lost to glaucoma cannot be restored. Treatment aims to lower the pressure in the eye to protect the optic nerve and slow or stop further damage. Depending on the type and stage of glaucoma, options include prescription eye drops, laser treatment or surgery. Treatment is usually long term, and it depends on using drops exactly as prescribed and keeping follow-up visits. Your optometrist will explain the options and refer you when needed.
How often should I be screened?
Glaucoma screening is part of a complete eye exam. We recommend an eye exam every two years for adults, and every year from age 65 or if you have risk factors. If you are already followed for glaucoma or as a glaucoma suspect, your optometrist will set the schedule.
Is it covered?
RAMQ covers one complete eye exam a year for people 65 and over and for children under 18 (we see children from age 4). Some additional tests, such as imaging, are not covered by RAMQ, and we will tell you the cost before doing one. Many private insurance plans cover eye exams and testing, and we bill most major insurers directly.
Common questions
Can I have glaucoma if my vision seems fine?
Yes. Early glaucoma usually causes no symptoms, and central vision often stays clear until late. That is why the optic nerve and your side vision are checked even when you see well.
Does the OCT scan hurt?
No. OCT uses light, nothing touches the eye, and each scan takes a few seconds while you look at a target.
Is the air-puff test the same as a glaucoma test?
Not quite. Measuring eye pressure, sometimes with a puff of air, is only one part of screening. Because glaucoma can occur at normal pressure, a full screening also looks at the optic nerve, often with OCT imaging, and at your side vision with a visual field test.
Is glaucoma hereditary?
Glaucoma can run in families. If a parent, brother or sister has glaucoma, your risk is higher, so tell your optometrist, who may suggest more frequent checks.
Can glaucoma be cured?
There is no cure, and lost vision does not come back, but treatment can slow or stop further damage. Regular follow-up is the key to keeping the vision you have.
Book an eye exam
Book online or call 514-827-7463. PrimeVision is at 9520 Bd de l'Acadie, Suite 222, Montréal. See also: what our eye exams in Montréal include, and the role of our optometrists in Montréal.
Our clinic is in Ahuntsic-Cartierville, near Marché Central. For directions, see our page on our optometrist in Ahuntsic, near Marché Central.