👁️ Chronic Glaucoma (most often Primary Open-Angle Glaucoma, POAG) is a progressive optic neuropathy caused by raised or poorly tolerated intraocular pressure (IOP). 💡 It is the leading cause of irreversible blindness worldwide. Insidious onset = patients often asymptomatic until advanced → “silent thief of sight.”

📖 About

Definition: Progressive optic neuropathy with optic disc cupping + visual field loss, often associated with raised IOP.
Epidemiology: Prevalence ↑ with age; affects ~2% of people >40 years, up to 10% >75 years.
Risk: Major cause of preventable blindness; earlier detection critical.

🧬 Aetiology & Risk Factors

↑ IOP due to reduced aqueous humour outflow (trabecular meshwork dysfunction).
Genetics: family history ↑ risk 4–9×.
Age >40, especially elderly.
Ethnicity: African descent → higher risk & earlier onset.
Myopia, diabetes, hypertension, corticosteroid use.
Normal-tension glaucoma: optic neuropathy despite IOP ≤21 mmHg.

⚙️ Pathophysiology

Aqueous humour produced by ciliary body → trabecular meshwork → Schlemm’s canal.
In POAG, trabecular outflow gradually impaired.
↑ IOP damages retinal ganglion cells → optic nerve head cupping → peripheral field loss.
Progressive, irreversible retinal ganglion cell apoptosis.

🩺 Clinical Features

Symptoms: Usually none until advanced. Late: peripheral vision loss → tunnel vision. Central vision preserved until end stage.
Signs:
- Optic disc cupping (cup:disc ratio >0.7 or asymmetry).
- Nasal step & arcuate scotoma on perimetry.
- Raised IOP (>21 mmHg), though not always.
- Open anterior chamber angle on gonioscopy.

🔎 Investigations

Tonometry: Measure IOP.
Ophthalmoscopy: Disc cupping, rim thinning.
Visual fields (perimetry): Arcuate defects, nasal step, peripheral loss.
Optical Coherence Tomography (OCT): Retinal nerve fibre layer thinning.
Gonioscopy: Confirms open angle (to differentiate from angle-closure).

⚡ Management (NICE & international guidelines)

Lifestyle: Regular follow-up, driving advice, adherence to drops.
Medical: First-line = prostaglandin analogues (latanoprost, bimatoprost) → ↑ uveoscleral outflow. Alternative/additional: – Beta-blockers (timolol) → ↓ aqueous production. – Carbonic anhydrase inhibitors (dorzolamide). – Alpha-agonists (brimonidine).
Laser: Selective Laser Trabeculoplasty (SLT) → increasingly first-line in NICE guidelines (2022).
Surgery: Trabeculectomy (gold standard), drainage devices, MIGS (minimally invasive glaucoma surgery).
Normal-tension glaucoma: Aim to lower IOP by ≥30% from baseline.

📉 Complications

Progressive irreversible visual field loss → blindness.
Falls, accidents due to poor peripheral vision.
Psychological impact: anxiety, depression.

📝 Teaching Pearls

💡 Exam favourite: POAG = raised IOP + cupped disc + field loss + open angle. – Silent thief: often asymptomatic until late. – Differentiate from acute angle-closure (painful red eye). – SLT is now recommended by NICE as first-line in many patients.

📊 Quick Comparison: Chronic vs Acute Glaucoma

🔹 Chronic (POAG): Insidious, painless, bilateral, gradual peripheral loss, disc cupping.
🔹 Acute angle-closure: Sudden, painful, red eye, halos, nausea/vomiting, corneal haze, very high IOP.

📚 References

NICE NG81: Glaucoma Diagnosis and Management (2022)
European Glaucoma Society Guidelines 5th Ed (2020)
Kanski’s Clinical Ophthalmology, 9th Ed

👁️ Case 1 — Asymptomatic Detection (Chronic Open-Angle Glaucoma)

A 67-year-old man attends a routine optician appointment and is found to have raised intraocular pressure and optic disc cupping, though he has no visual complaints. Formal visual field testing shows peripheral field loss. 💡 Chronic open-angle glaucoma is typically asymptomatic until late stages, with gradual peripheral vision loss. Screening by optometrists is key. First-line treatment is topical prostaglandin analogues (e.g. latanoprost) to lower intraocular pressure, with long-term monitoring to preserve vision.

👁️ Case 2 — Symptomatic Progressive Vision Loss (Chronic Open-Angle Glaucoma)

A 74-year-old woman presents with difficulty driving at night and “tunnel vision” gradually worsening over several years. She has a family history of glaucoma. Examination shows bilateral optic disc cupping and arcuate scotomas on visual field testing. 💡 Chronic glaucoma leads to progressive optic neuropathy, most marked in peripheral vision before central loss. Risk factors include age, family history, and African ancestry. Management involves topical agents, laser trabeculoplasty, or surgical trabeculectomy if pressure remains uncontrolled.

🚨 Case 3 — Acute Angle-Closure Glaucoma

A 62-year-old woman develops sudden severe ocular pain, blurred vision with haloes around lights, and headache with nausea. Examination shows a red eye with a fixed mid-dilated pupil and corneal haze. 💡 Acute angle-closure glaucoma occurs when the peripheral iris blocks aqueous humour outflow, leading to a rapid rise in intraocular pressure. It is an ophthalmic emergency requiring immediate treatment with IV acetazolamide, topical beta-blockers, and definitive laser iridotomy to prevent permanent vision loss.

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Chronic Glaucoma