Glaucoma is called the "silent thief of sight" for a reason. By the time most patients notice a change in their vision, irreversible damage has already been done. Understanding how glaucoma works — and why early detection is the only reliable defence — could be the most important thing you read this year.
What exactly is glaucoma?
Glaucoma is not a single disease but a group of conditions that damage the optic nerve, the cable that carries visual information from your eye to your brain. In the majority of cases, this damage is caused by abnormally high pressure inside the eye — what doctors call elevated intraocular pressure (IOP).
Your eye continuously produces a clear fluid called aqueous humour. Normally this fluid drains away at the same rate it is produced, keeping pressure stable. In glaucoma, that drainage system becomes blocked or inefficient, pressure builds, and the optic nerve slowly deteriorates.
- Glaucoma is the leading cause of irreversible blindness in Africa, accounting for an estimated 15% of all blindness on the continent.
- Nigeria has one of the highest prevalences of primary open-angle glaucoma in the world — affecting up to 7% of adults over 40.
- Vision lost to glaucoma cannot be restored. Only early detection and treatment can preserve what remains.
- Most patients with early glaucoma have no symptoms at all — no pain, no blurring, no visible change.
The two main types
Primary open-angle glaucoma (POAG)
This is by far the most common form, and the most deceptive. The drainage angle in the eye remains open, but the drainage system itself is inefficient — like a slow drain rather than a blocked one. Pressure rises gradually over years. Peripheral vision erodes so slowly that patients rarely notice until late in the disease. This is the type that disproportionately affects people of African descent.
Angle-closure glaucoma
Here the drainage angle is physically blocked by the iris. It can develop slowly (chronic) or suddenly (acute). Acute angle-closure glaucoma is a medical emergency — patients experience sudden, severe eye pain, blurred vision, halos around lights, nausea, and headache. If you or someone with you experiences these symptoms, go directly to an emergency eye clinic. Do not wait.
"In primary open-angle glaucoma, the peripheral vision goes first — and peripheral vision is exactly the kind of thing the brain learns to compensate for. That is why patients come in telling us nothing is wrong, and then we show them their visual field test."
Who is at risk?
Glaucoma can affect anyone, but several factors significantly raise your risk:
- Age over 40 — risk increases with every decade after 40
- African ancestry — POAG is 6–8 times more common in people of African descent
- Family history — having a first-degree relative with glaucoma raises your risk by 4–9 times
- High intraocular pressure — even without diagnosed glaucoma, elevated IOP is a major risk factor
- Diabetes and hypertension — both associated with increased glaucoma risk
- High myopia (short-sightedness) — particularly for open-angle glaucoma
- Long-term corticosteroid use — including eye drops prescribed for other conditions
Important note on steroid eye drops: Over-the-counter and prescription steroid drops — sometimes used for allergies or skin conditions applied near the eyes — can raise intraocular pressure significantly over time. Always inform your eye doctor of all medications and drops you use.
How glaucoma is diagnosed
A comprehensive glaucoma assessment at The Eye Doctors includes several tests, none of which are uncomfortable:
- Tonometry — measures intraocular pressure
- Ophthalmoscopy — direct examination of the optic nerve for signs of damage or cupping
- Visual field testing (perimetry) — maps your full field of vision to detect any peripheral loss
- OCT imaging — optical coherence tomography produces a detailed cross-section of the optic nerve and surrounding retinal nerve fibre layer, detecting damage before it shows on a visual field test
- Gonioscopy — examines the drainage angle to classify glaucoma type
We recommend that anyone over 40 — especially those with any of the risk factors above — has a full glaucoma screen at least every two years. For those with a family history, we advise beginning screening at 35.
Treatment options
Glaucoma is not curable, but it is highly manageable. The goal of all treatment is to lower intraocular pressure enough to stop or significantly slow optic nerve damage.
Eye drops
For most patients, treatment begins with prescription eye drops taken once or twice daily. These either reduce the amount of fluid the eye produces or improve drainage. Consistency is critical — missing drops allows pressure to spike and damage to continue.
Laser treatment
Selective laser trabeculoplasty (SLT) uses brief pulses of laser energy to improve fluid drainage. It is a painless outpatient procedure that takes about 10 minutes per eye. For many patients it can replace or reduce reliance on daily drops, and can be repeated if needed.
Surgery
When drops and laser do not achieve sufficient pressure control, surgery creates a new drainage pathway. The most common procedure is trabeculectomy. Modern minimally invasive glaucoma surgeries (MIGS) offer effective pressure reduction with faster recovery times and lower complication rates — your surgeon will advise which approach is appropriate for your case.
"The most common reason glaucoma progresses despite treatment is not the medication failing — it is patients stopping their drops because they feel fine. Glaucoma has no symptoms. That is precisely why you must treat it even when you cannot feel it doing damage."
Living with glaucoma
A glaucoma diagnosis is not a sentence to blindness. With proper management and consistent follow-up, most patients maintain functional vision for life. Regular monitoring appointments — typically every 3 to 6 months — allow your doctor to track any progression and adjust treatment early.
Inform your first-degree relatives (parents, siblings, children) of your diagnosis. Given the hereditary component, they should be screened regardless of whether they have symptoms.