Primary Open-Angle Glaucoma (POAG)

Features

•    Painless, gradual peripheral (tunnel) visual field loss

•    Usually bilateral but asymmetric

•    Optic disc cupping (increased cup-to-disc ratio)

•    Thinning of neuroretinal rim

Pathophysiology

•    Reduced aqueous outflow via trabecular meshwork

•    Chronic, progressive optic neuropathy

Risk factors

•    Age >40

•    FHx

•    African ancestry

•    Myopia

•    Diabetes, hypertension

Treatment

•    First-line: Prostaglandin analogues (e.g., latanoprost) — ↑ uveoscleral outflow

•    Beta-blockers (e.g., timolol) — ↓ aqueous production

•    Carbonic anhydrase inhibitors (e.g., dorzolamide)

•    Alpha-agonists (e.g., brimonidine)

•    Laser trabeculoplasty or trabeculectomy if uncontrolled

Acute Angle-Closure Glaucoma

Features

•    Painful, sudden onset

•    Red eye, blurred vision, haloes around lights

•    Hard eye on palpation

•    Mid-dilated, fixed pupil

•    Nausea, vomiting

Pathophysiology

•    Mechanical blockage of trabecular meshwork by iris

•    Precipitated by mydriasis (e.g., dim light, medications)

Risk factors

•    Hypermetropia (small anterior chamber)

•    Elderly, East Asian ethnicity

•    Family history

Management

•    Emergency — vision-threatening

•    Immediate medical:

o    IV acetazolamide (reduces aqueous production)

o    Topical beta-blocker and pilocarpine (after initial IOP reduction)

•    Analgesia and antiemetics

•    Definitive: Laser peripheral iridotomy (both eyes)

Secondary Glaucoma

Causes

•    Uveitis (inflammatory debris obstructing trabecular meshwork)

•    Trauma (angle recession, hyphema)

•    Steroid-induced (steroid responders)

•    Neovascular (diabetes, CRVO)

Features

•    Depend on underlying cause; may mimic open or closed-angle presentations

Extra Revision Pearls

•    Painless peripheral loss clue → POAG; painful red eye clue → AACG

•    Cup-to-disc ratio clue → >0.7 suggests glaucomatous damage

•    Halos clue → corneal oedema from raised IOP (AACG) or cataract

•    Hypermetropia clue → risk of angle-closure (shallow anterior chamber)

•    Myopia clue → risk of POAG and retinal detachment

•    Steroids clue → check for secondary glaucoma regularly