Glaucoma is a group of eye diseases in which the optic nerve — the cable connecting the eye to the brain — is progressively damaged, leading to irreversible vision loss. In most cases, elevated intraocular pressure (IOP) is the main risk factor, but some develop glaucoma even with normal IOP (normal tension glaucoma). Glaucoma is the most common cause of permanent blindness globally, affecting approximately 80 million people. The tragedy: the most common form (primary open-angle glaucoma) is entirely painless and symptomless until most peripheral vision is already lost — making regular eye examinations essential for early detection.

What are the symptoms of glaucoma?

Primary open-angle glaucoma (POAG, 70-80% of cases): NO symptoms in early to moderate disease. Peripheral vision is lost first — forming arcuate visual field defects — but the brain fills in the gaps from the other eye and the person is unaware. When central vision is finally affected, the disease is at a very advanced stage. Acute angle-closure glaucoma: sudden onset severe eye pain, headache, nausea/vomiting, blurred vision, halos around lights, red eye, pupil semi-dilated and fixed — a medical emergency. Secondary glaucoma: may have symptoms from the underlying cause (uveitis, pseudoexfoliation).

What causes glaucoma?

The primary modifiable risk factor: elevated intraocular pressure (IOP >21 mmHg). Non-modifiable risk factors: older age; family history (10× higher risk if a first-degree relative affected); African or Caribbean descent (higher POAG prevalence and more severe at presentation); East Asian descent (higher angle-closure risk from anatomically narrow angles); high myopia (POAG risk); steroid use (corticosteroid-induced glaucoma). Normal tension glaucoma risk factors: low diastolic blood pressure, migraines, vasospasm — suggesting vascular mechanisms also drive optic nerve damage.

What is the treatment for glaucoma?

All treatment targets IOP reduction — the only proven way to slow optic nerve damage. First-line options (NICE/EGS 2022): Selective laser trabeculoplasty (SLT): now recommended as first-line for newly diagnosed POAG/OHT (LiGHT trial evidence). Or Prostaglandin analogue drops (latanoprost, travoprost, bimatoprost): once nightly; approximately 25-30% IOP reduction. Other drops: beta-blockers (timolol); carbonic anhydrase inhibitors (dorzolamide — topical; acetazolamide — systemic); alpha-2 agonists (brimonidine). Surgical: trabeculectomy (bleb surgery) — most effective IOP reduction for advanced disease; MIGS (minimally invasive). Acute angle-closure: IV acetazolamide + topical drops + mannitol + laser iridotomy.

Can glaucoma be prevented?

The optic nerve damage from glaucoma cannot be reversed — prevention is about preventing progression by detecting the disease early and treating it. Population-level prevention: regular eye examinations including IOP measurement and optic disc assessment for all adults ≥40 years (especially with risk factors — family history, African/Caribbean descent, myopia, diabetes); more frequent screening for high-risk groups (≥35 years for those with a parent or sibling with glaucoma). Reducing corticosteroid use where possible reduces corticosteroid-induced glaucoma risk. No dietary or lifestyle modifications have been shown to prevent POAG.

How does GMJ News cover glaucoma?

GMJ News covers WHO glaucoma data, the "silent thief of sight" diagnosis problem, SLT first-line evidence (LiGHT trial), prostaglandin analogues, trabeculectomy, acute angle-closure emergency, normal tension glaucoma, corticosteroid-induced glaucoma, and MIGS. Glaucoma — the leading cause of irreversible blindness — is directly relevant to PHIG's NCD programme and ophthalmology service development in Georgia.

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Glaucoma

GMJ News knowledge hub · last reviewed September 2026 · Georgian Medical Journal

Summary Statistics Glossary GMJ news FAQ Documents Organizations Research

Glaucoma — the leading cause of irreversible blindness globally — affects approximately 80 million people worldwide and has blinded approximately 8 million bilaterally, yet remains profoundly underdiagnosed because primary open-angle glaucoma (POAG — the most common form) is entirely painless until 30-50% of optic nerve fibres have been permanently lost — earning it the title the “silent thief of sight” (WHO). The 2022 Laser in Glaucoma and Ocular Hypertension (LiGHT) trial changed first-line treatment by demonstrating that selective laser trabeculoplasty (SLT) is superior to eye drops as initial therapy — producing better IOP control, fewer required drops, and lower long-term treatment burden while achieving the same goal of slowing optic nerve damage.

Key messages

80M affected — most common cause of irreversible blindness

80 million people have glaucoma; 8 million are bilaterally blind from it. Glaucoma is the most common cause of irreversible blindness globally — yet is largely preventable with early detection and treatment (WHO 2020).

Silent thief of sight — no symptoms until late

Primary open-angle glaucoma (POAG) is entirely painless and asymptomatic until approximately 30-50% of optic nerve fibres have been permanently lost — earning it the title the "silent thief of sight." Regular eye examinations are the only way to detect POAG before significant vision is lost.

SLT — now recommended as first-line over drops

The LiGHT trial (2019) demonstrated that selective laser trabeculoplasty (SLT) as first-line treatment for newly diagnosed POAG/OH achieves superior IOP control vs eye drops, fewer escalations, better quality of life, and lower long-term treatment burden. NICE and EGS now recommend SLT as first-line.

Prostaglandin analogues — first-line drops

If eye drops are used: prostaglandin analogues (latanoprost 0.005%, travoprost, bimatoprost — once nightly) are the most effective class for IOP reduction (approximately 25-30% IOP reduction) and best tolerated. They increase aqueous humour outflow via the uveoscleral pathway.

Acute angle-closure — medical emergency

Acute angle-closure glaucoma: sudden severe eye pain, blurred vision, halos around lights, headache, nausea/vomiting, hard red eye — from dramatically elevated IOP (50-80 mmHg). Medical emergency requiring immediate IV acetazolamide, topical IOP-lowering drops, systemic hyperosmotic agents (IV mannitol), followed by laser iridotomy.

IOP is not everything — normal tension glaucoma

Normal tension glaucoma (NTG) — progressive optic nerve damage despite IOP consistently ≤21 mmHg — occurs in approximately 30% of POAG cases. Vascular mechanisms (disc ischaemia) and other factors drive neuronal loss. Still benefits from IOP lowering (reduces progression by approximately 50% even in NTG).

Key statistics

80M

people with glaucoma globally (WHO 2020)

WHO 2020

bilaterally blind from glaucoma globally

WHO

most common cause of irreversible blindness globally

WHO

30-50%

optic nerve fibres lost before symptoms appear in POAG

EGS/AAO

SLT

selective laser trabeculoplasty — now NICE/EGS first-line for POAG

LiGHT 2019/NICE

~30%

of POAG has normal-tension glaucoma (IOP ≤21mmHg)

EGS

Glaucoma types and relative prevalence globally (WHO/EGS)

Source: WHO/EGS. POAG dominates in most regions; ACG more common in East Asia; NTG ~30% of all POAG.

Glossary of key terms

Intraocular pressure (IOP)
WHO/EGSThe fluid pressure inside the eye — generated by balance between aqueous humour production (ciliary body) and drainage (trabecular meshwork → Schlemm's canal in POAG; uveoscleral pathway in physiological outflow). Normal IOP: 10-21 mmHg. In most glaucoma: elevated IOP damages optic nerve fibres. IOP is measured by tonometry (Goldman applanation tonometry — gold standard; non-contact tonometry — screening). The pressure at which optic nerve damage occurs varies by individual (some at 25 mmHg; some at 18 mmHg — normal tension glaucoma).

Primary open-angle glaucoma (POAG)
WHO/EGSThe most common glaucoma form — characterised by open iridocorneal angle (aqueous can access the trabecular meshwork) but elevated IOP from reduced outflow facility. Damage: progressive loss of retinal ganglion cells → optic nerve cupping → visual field loss (arcuate scotoma; nasal step) → peripheral vision loss → tunnel vision → total blindness if untreated. Painless; diagnosed at screening or routine eye examination.

Optic disc cupping
EGS/WHOThe optic disc (the optic nerve head visible on fundoscopy) has a central pale cup and surrounding pink neuroretinal rim. The cup-to-disc (C:D) ratio measures the proportion of the disc occupied by the cup. Normal C:D ≤0.5. In glaucoma: progressive enlargement of the cup (cupping) as ganglion cell axons are lost → C:D >0.6, notching of the neuroretinal rim, nasal displacement of vessels (bayonetting). Asymmetric C:D between eyes is suspicious.

Selective laser trabeculoplasty (SLT)
NICE/LiGHTA laser procedure targeting melanin-containing trabecular meshwork cells — using low-energy 532nm Nd:YAG laser to stimulate macrophage activity and remodelling of trabecular meshwork → improved aqueous outflow → IOP reduction of approximately 25-30%. Advantages over drops: no daily adherence required; works without patient compliance; can be repeated (unlike argon laser trabeculoplasty); evidence from LiGHT trial (2019): SLT as first-line achieves better IOP control at 3 years vs drops.

Trabeculectomy
EGSA surgical drainage procedure — creating a new outflow channel (bleb) under the conjunctiva bypassing the damaged trabecular meshwork. The most effective surgical IOP reduction (achieves low IOP impossible with drops). Used when medical and laser treatment has failed. Complications: bleb failure, hypotony, endophthalmitis, cataract acceleration. Newer MIGS (minimally invasive glaucoma surgery) procedures (iStent, Hydrus, OMNI) offer lower risk with moderate IOP reduction.

Corticosteroid-induced glaucoma
EGS/WHOProlonged topical, intraocular, inhaled or systemic corticosteroid use can raise IOP in genetically susceptible individuals (approximately 5-8% — high steroid responders). Risk is highest with topical ophthalmic steroids. All patients on chronic corticosteroids (including inhaled in COPD/asthma) should have regular IOP monitoring. May progress to glaucoma. Management: switch to lower-risk steroid; add IOP-lowering drops; consider trabeculectomy.