“What is glaucoma”
Glaucoma is a group of eye diseases that damage the optic nerve, the cable carrying visual information from the eye to the brain, and is often linked to raised pressure inside the eye. This overview draws on six patient-facing summaries from six independent medical sources; no single source supports more than one-sixth of the material.
Left: the eye's optic nerve carries sight to the brain; raised fluid pressure can damage it. Right: what a person may see at each stage — the most common form is symptom-free early, then peripheral vision fades. Simulated views, illustrative only.
Symptoms vary by type and stage. Early open-angle and normal-tension glaucoma often have no symptoms at all; peripheral (side) vision is gradually lost. Angle-closure disease can announce itself with eye pain, headache, halos or coloured rings around lights, a red eye, and blurred vision — sometimes in short spells that fade after sleep and return.
Glaucoma can be found early through regular comprehensive eye examinations: vision testing, eye-pressure measurement with a small probe, and examination of the optic nerve. People with warning signs of a closing drainage angle, or limited access to eye care, may be advised to have a preventive laser iridotomy.
Treatment lowers pressure inside the eye. Options include prescription eye drops, oral medicines, laser procedures (such as laser iridotomy) and surgery, alone or in combination. For an acute attack, hospital treatment with pressure-lowering drugs and laser or surgery can leave very little damage if given promptly.
Damage to the optic nerve is permanent, so the goal of care is protecting the sight that remains. With early diagnosis and treatment, serious vision loss can often be prevented — which is why routine eye examinations matter even when the eyes feel entirely normal.
Sudden severe eye pain or headache, a red eye, blurred or foggy vision, halos or coloured rings around lights, nausea or vomiting may indicate acute angle-closure glaucoma. This is a true emergency: go to an emergency department or emergency eye clinic straight away — immediate examination and treatment are vision-saving.
This report is general information, not a diagnosis. If you have concerns about your own eyes or vision, arrange a comprehensive eye examination with an eye-care professional.
| Source | Title | Definition (as stated) | Emergency guidance |
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Six patient-facing glaucoma summaries, one row per independent host (CDC, Glaucoma UK, NHS Gloucestershire, Johns Hopkins Wilmer ×2 hosts, Mayo Clinic), reviewed for this report; columns cover definition, symptoms, emergency symptoms, treatment and screening. Full symptom and treatment text is condensed above for space. The lead visual is an illustrative diagram, not measured data.