Glaucoma: What Ontario Patients Need to Know
Glaucoma is a leading cause of irreversible blindness worldwide. It has no early symptoms — the only way to detect it is through a comprehensive eye exam. Here is what every Ontario adult should know.
Updated · Dr. David Wilkinson
Glaucoma affects an estimated 250,000 Canadians, and half of them don't know they have it. It is called the "silent thief of sight" because peripheral vision is lost gradually and painlessly — patients rarely notice until the damage is severe.
Types of glaucoma
Open-angle glaucoma (most common)
The drainage angle of the eye remains open but the drainage meshwork is partially blocked, causing pressure to build slowly over years. No pain, no redness, no symptoms in the early stages.
Angle-closure glaucoma
The drainage angle becomes blocked suddenly (acute) or gradually (chronic). Acute angle-closure is a medical emergency: sudden severe eye pain, headache, nausea, blurred vision, and halos around lights. Go to emergency immediately.
Normal-tension glaucoma
Optic nerve damage occurs despite measurements of normal intraocular pressure. Generally considered a subtype of open-angle glaucoma. More common in people of Japanese ancestry.
Who is at risk
Your risk is significantly elevated if you have:
- A first-degree family member with glaucoma — your risk is 4–9 times higher
- Age over 60
- African or Caribbean ancestry — glaucoma onset is earlier and more severe on average
- Elevated intraocular pressure detected at an eye exam
- Thin central corneal thickness
- High myopia (strong nearsightedness)
- Long-term corticosteroid use (inhaled, topical, or systemic)
How glaucoma is detected
A comprehensive eye exam includes:
- Tonometry — measures intraocular pressure (the "air puff" or Goldman applanation test)
- Ophthalmoscopy — examination of the optic nerve for signs of damage
- Visual field testing — maps peripheral vision; defects are characteristic of glaucoma
- OCT (optical coherence tomography) — measures retinal nerve fibre layer thickness; can detect damage before vision loss occurs
- Gonioscopy — examines the drainage angle; required to classify glaucoma type
No single test is definitive. Glaucoma diagnosis requires a combination of findings over time.
Glaucoma and intraocular pressure
The normal range for IOP is approximately 10–21 mmHg. Elevated pressure is the most significant modifiable risk factor — treatment focuses on lowering it. However:
- Some people with IOP above 21 mmHg never develop glaucoma (ocular hypertension)
- Some develop glaucoma with normal pressure (normal-tension glaucoma)
This is why the full examination — not just a pressure check — matters.
Living with glaucoma
Glaucoma is a lifelong condition that requires ongoing monitoring. With proper treatment adherence, most patients retain functional vision throughout their lifetime. Key points:
- Eye drops must be used consistently — missing doses allows pressure to spike
- Reassessment every 6–12 months tracks progression
- Regular follow-up is essential once diagnosed
If you are at elevated risk, discuss screening frequency with your optometrist. Many Ontario optometry clinics have OCT equipment and can conduct comprehensive glaucoma assessments.
Toronto Eye Care
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Spadina Optometry serves patients across Toronto and the surrounding area. Our optometrists provide comprehensive eye exams, contact lens fittings, and more.
Book an appointment →Frequently Asked Questions
- What is glaucoma?
- Glaucoma is an eye disease that involves damage to the optic nerve, often associated with elevated intraocular pressure (IOP). The optic nerve carries visual information from the eye to the brain. Glaucoma causes progressive, irreversible peripheral vision loss that is usually unnoticeable until significant damage has occurred.
- Does OHIP cover eye exams for glaucoma in Ontario?
- Yes. Adults with diagnosed glaucoma are eligible for OHIP-insured eye exams regardless of age.
- What are the risk factors for glaucoma?
- Key risk factors include: elevated intraocular pressure, age over 60, a family history of glaucoma (first-degree relative), African or Caribbean ancestry, a history of eye injury or surgery, thin corneas, and long-term use of corticosteroids. People with any of these factors should be screened regularly.
- Can glaucoma be cured?
- There is currently no cure for glaucoma. Damage to the optic nerve is permanent and irreversible. However, glaucoma can be effectively managed with eye drops, laser treatment, or surgery to lower intraocular pressure and halt further damage. Early detection is critical.
- How is glaucoma treated in Ontario?
- First-line treatment is typically prescription eye drops that lower intraocular pressure. If drops are insufficient, laser trabeculoplasty is a common next step. Surgical options include trabeculectomy and minimally invasive glaucoma surgery (MIGS).
Author
Dr. David Wilkinson, OD, FAAO — Pending clinical review
Optometrist, Spadina Optometry
A Toronto native and Fellow of the American Academy of Optometry, Dr. David Wilkinson has been part of our optometric practice since earning his OD from the Illinois College of Optometry in 2007. A certified clinical investigator with a special interest in contact lenses and myopia management, he serves as a part-time Clinical Instructor at the University of Waterloo's Waterloo Eye Institute and previously spent nearly a decade as Practice Advisor at the College of Optometrists of Ontario.