Glaucoma
The silent thief of sight — painless, permanent, and detectable years before you notice
What it is
Glaucoma is progressive damage to the optic nerve, usually — but not always — associated with raised pressure inside the eye. It destroys peripheral vision first, and it does so slowly, painlessly, and symmetrically enough that the brain fills in the missing pieces. That combination is why it is called the silent thief of sight: by the time a person NOTICES they have lost vision, a substantial and permanently irrecoverable amount of optic nerve has already gone. Vision lost to glaucoma never comes back. The entire point of glaucoma care is therefore detection before symptoms — which means an eye test.
Why it matters
Because it is one of the very few diseases where the whole game is screening, and where the intervention is free at the point of decision: GO AND HAVE AN EYE TEST. Glaucoma is a leading cause of irreversible blindness worldwide, a large fraction of people who have it do not know, and treatment — drops or laser — is effective at halting progression. Everything that can be saved is saved by finding it early, and nothing that has been lost can be recovered late. There is also a crucial nuance that gets missed: EYE PRESSURE IS A RISK FACTOR, NOT THE DISEASE. Normal-tension glaucoma is real and common, and a normal pressure reading does not exclude glaucoma — the optic nerve has to be looked at.
What BioSignal knows about treating this
What works for Glaucoma
BioSignal’s clinical summary, most important first.
- HAVE AN EYE TEST — this is the intervention. Glaucoma is painless and symptomless until vision has already been permanently lost, and it is found by looking. If you have a family history, or are of African or Caribbean ancestry, start earlier and go more often
- TREAT IT AND KEEP TREATING IT — pressure-lowering eye drops (usually a prostaglandin analogue) halt progression, and adherence is the single biggest determinant of whether someone keeps their sight. People stop the drops because the disease has no symptoms, which is precisely the problem
- SELECTIVE LASER TRABECULOPLASTY (SLT) — the LiGHT trial showed laser as first-line treatment is effective and reduces the need for drops. It is a genuine option to ask about, and many people are never offered it
- Surgery (trabeculectomy or minimally invasive procedures) where drops and laser are insufficient
- GO TO AN EMERGENCY DEPARTMENT for a painful red eye with haloes, headache and vomiting — acute angle-closure glaucoma destroys sight within hours and is a genuine emergency
- Tell your family — glaucoma is strongly heritable, and first-degree relatives should be screened. This is one of the most useful things a diagnosed person can do
- Understand what treatment does: it PRESERVES the vision you still have. It does not restore what has gone
Signal Records relevant to this condition
Interventions and contributing factors — some of these records describe a cause rather than a cure. The rating shown is BioSignal’s confidence in that Signal Record, not a claim about how well it treats this condition. Open any of them for the full evidence.
New to this? Read these first
How this usually unfolds
- Recognize risk factors
- Get diagnosed
- Track key biomarkers
- Lifestyle first
- Evidence-based treatment
- Long-term monitoring
Who is at risk
- Age
- FAMILY HISTORY — a first-degree relative with glaucoma substantially raises risk, and is a reason for regular screening from an earlier age
- African, Caribbean or Hispanic ancestry — earlier onset and more aggressive disease
- Raised intraocular pressure — a risk factor, not the diagnosis
- Severe short-sightedness (myopia)
- Diabetes
- Long-term corticosteroid use, including eye drops and inhalers
- Previous eye injury
How it's diagnosed
Glaucoma is detected by looking at the optic nerve, measuring the pressure, and testing the visual field — and it is found, overwhelmingly, at routine eye tests in people with no symptoms whatsoever. That is the whole point of the routine eye test, and it is why it is not merely a way of selling spectacles. The single most important nuance is that pressure alone is not diagnostic in either direction: many people with raised pressure never develop glaucoma, and a substantial proportion of people WITH glaucoma have entirely normal pressure. The optic nerve is what tells you.
Key biomarkers
Lifestyle
Explore this condition across BioSignal
Related Foundations
Related Signal Records
Frequently asked questions
Would I know if I had glaucoma?
Almost certainly not, and that is the entire problem. The common form of glaucoma is completely painless and takes your PERIPHERAL vision first — and your brain is extremely good at filling in missing peripheral information, so you do not perceive a gap. By the time a person notices something is wrong with their sight, a large and permanently irrecoverable amount of optic nerve has already been destroyed. This is why glaucoma is found at routine eye tests, in people who feel perfectly fine, and why 'my eyes seem fine' is not a reason to skip one. It is the closest thing in medicine to a disease that only screening can catch in time.
My eye pressure is normal. Doesn't that rule it out?
No, and this is a genuinely important misunderstanding. Raised eye pressure is a RISK FACTOR for glaucoma — it is not the disease. NORMAL-TENSION GLAUCOMA is real and is far from rare: people develop progressive optic nerve damage and lose vision with pressures that are entirely within the normal range. Conversely, plenty of people have raised pressure and never develop glaucoma at all. The disease is damage to the OPTIC NERVE, and that is what has to be examined — which is why the eye test involves looking at the back of your eye and testing your visual field, not just puffing air at it.
Can vision lost to glaucoma be restored?
No. This is the hardest fact on this page and it is the reason for all the urgency about screening. Optic nerve fibres that have been destroyed do not regenerate, and the vision they carried is gone permanently. Treatment — drops, laser, surgery — works by lowering the pressure and halting further damage. It PRESERVES what you have. It cannot give back what has already gone. Every month of delay is a permanent, non-negotiable loss, which is why finding it before symptoms is not a nice-to-have.
Why should I keep taking drops when nothing hurts?
Because nothing hurting is what glaucoma feels like right up until you are going blind. This is the central difficulty of treating it: the disease is silent, the drops are a daily nuisance, they can sting, and stopping them produces no immediate consequence whatsoever — for a while. Adherence is the single biggest determinant of whether a person with glaucoma keeps their sight, and it is poor, for entirely human reasons. If the drops are the problem, say so: laser (SLT) is an effective first-line alternative that many people are never offered, and asking about it is reasonable.
When is an eye problem an emergency?
A painful red eye with blurred vision, haloes around lights, a severe headache, and nausea or vomiting is ACUTE ANGLE-CLOSURE GLAUCOMA until proven otherwise — and it is a true emergency, in which the pressure inside the eye rises dramatically and sight can be lost within HOURS. It is sometimes mistaken for a migraine, or for a stomach bug because of the vomiting. Go to an emergency department. This is a completely different disease from the slow, silent, chronic glaucoma that the rest of this page is about.
Evidence summary
Glaucoma is a progressive optic neuropathy and a leading cause of irreversible blindness worldwide; a substantial proportion of affected individuals are undiagnosed, as open-angle disease is asymptomatic until advanced visual field loss has occurred. Elevated intraocular pressure is a major risk factor but is neither necessary nor sufficient for the diagnosis: normal-tension glaucoma is common, and ocular hypertension frequently does not progress. Lowering intraocular pressure — pharmacologically, by laser, or surgically — is the only intervention shown to slow progression, and randomized evidence supports its efficacy. The LiGHT trial demonstrated that selective laser trabeculoplasty as first-line treatment is effective, reduces reliance on topical therapy, and is cost-effective. Vision already lost is not recoverable. Family history and African or Caribbean ancestry are associated with earlier onset and more aggressive disease and warrant earlier and more frequent screening. Acute angle-closure glaucoma is an ophthalmic emergency causing rapid, irreversible sight loss. No dietary or supplement intervention has established benefit.
References & sources
- NICE NG81 — Glaucoma: diagnosis and management
- LiGHT randomized trial of selective laser trabeculoplasty versus eye drops as first-line treatment
- Ocular Hypertension Treatment Study and the Early Manifest Glaucoma Trial
- WHO World Report on Vision
Educational information — not medical advice
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