The short version
Two conditions cause most avoidable sight loss in older adults in the UK, they behave in opposite ways, and the useful action for each is different.
| Glaucoma | Macular degeneration | |
|---|---|---|
| Takes | Peripheral vision first | Central vision first |
| You notice | Nothing, until it is late | Distortion, then a blur in the middle |
| Reversible? | No. Damage is permanent | No, but wet AMD can be halted |
| The action | Get tested — there is no self-check | Act fast on new distortion |
| Read | Glaucoma | Macular degeneration |
Four things worth doing
Book a sight test, and find out if it is free
There is no national glaucoma screening programme, so a routine sight test is the detection route for both conditions. Whether yours is free depends on your age, your health, your income and which nation you live in, and the rules differ in each — check the current entitlement with NHS England, NHS Inform in Scotland, NHS 111 Wales or nidirect for Northern Ireland, or simply ask the optician when you book, because they check eligibility as a matter of routine.
Ask your relatives, and tell them
Family history is the strongest single risk flag for glaucoma and it is the one piece of information that is free to obtain. If you have it, so do your children.
Cover one eye, then the other, now and again
Both conditions are routinely missed in one eye because the other compensates completely. Ten seconds at a doorframe or a window will do it: look for lines that bend, or a patch that is missing.
Do not smoke
The largest modifiable risk factor for macular degeneration by a wide margin, and it is on the list for almost everything else on this site.
Five urgent patterns
Sudden painless loss of vision in one eye — possible retinal artery occlusion. This is a stroke of the eye and is treated as a stroke: call 999, not the optician. If it lasted minutes and then cleared completely, that is the eye's equivalent of a TIA and goes down the same-day TIA pathway — it is a warning, not a false alarm, and the warning is the useful part.
New flashes, a sudden shower of floaters, or a shadow or curtain across part of the vision — possible retinal detachment. Same day. The reason speed matters is specific: if your central vision is still intact, the detachment has not yet reached the macula, and repairing it before it does is what preserves reading vision.
Sudden severe eye pain with haloes around lights, a red eye, and nausea — possible acute angle-closure glaucoma. Same-day emergency eye care. It is sometimes mistaken for migraine or a stomach upset and the eye is never examined. The glaucoma chapter covers this in full.
Over 50, with sudden visual loss alongside a new headache at the temple, scalp tenderness, or jaw ache that comes on while chewing — possible giant cell arteritis. Same day, urgently. This one is on the list for a specific reason: untreated, it threatens the other eye within days, and the treatment that prevents that is started on suspicion rather than after a test.
New distortion — straight lines looking bent or wavy — possible wet macular degeneration. Same week, and treat it as same day if it is worsening. Injections mainly protect the sight you still have, and some people do get a little back.
What is being sold, and what it is worth
Two things are currently promoted heavily for glaucoma, and this site grades both rather than dismissing them.
- High-dose nicotinamide (vitamin B3). Real mechanism, striking mouse data, and two small positive human trials — but what those trials measured was an electrical signal from the retina and sensitivity at points on a visual field chart, not whether anyone could see better. The phase 3 trial reports in late 2027. Graded Emerging. The doses involved are pharmacological, not nutritional, and need liver monitoring.
- Slow-paced breathing. One randomised trial found about 2 mmHg of pressure reduction added to standard treatment. Unblindable, on a surrogate endpoint, and modest — but free and harmless, so there is no reason to talk anyone out of it alongside their treatment.
Both are covered in full in what is being sold for glaucoma. Neither replaces pressure-lowering treatment, and the one genuinely important thing to know about UK glaucoma care is on the glaucoma page: since 2022, NICE has recommended laser rather than lifelong drops as a first-line option, on the strength of a British trial. A great deal of published advice has not caught up.