FFinalistSouthampton · 2027
Ophthalmology
AKT · Ophthalmology/Glaucoma

Primary open-angle glaucoma

Chronic optic neuropathy with an open angle (raised IOP / disc cupping / field loss)

Overview

A chronic, progressive optic neuropathy with an open drainage angle, characteristically asymptomatic until advanced. Defined by optic-disc cupping and arcuate visual-field loss, usually with raised IOP. Detected on routine optometry. NICE (2022): first-line treatment is now 360° selective laser trabeculoplasty (SLT) for those with IOP ≥24 mmHg needing treatment.

Recognise

  • Insidious, painless, BILATERAL peripheral visual-field loss that the patient does not notice until late (tunnel vision)
  • Optic-disc cupping (increased cup:disc ratio, notching, bayoneting of vessels) and RNFL loss
  • Usually raised IOP (>21 mmHg); risk factors: age, family history, African-Caribbean ethnicity, myopia, diabetes

Red flags

  • Advanced field loss / very high IOP at presentation → expedite specialist treatment
  • Acutely painful red eye with haloes is angle-CLOSURE, not POAG

Differentials & how to tell them apart

Ocular hypertensionraised IOP with NORMAL disc and fields (no glaucomatous damage yet)
Normal-tension glaucomaglaucomatous disc/field damage with IOP in the normal range
Acute angle-closure glaucomaacute painful red eye — the opposite presentation
Other optic neuropathypallor rather than cupping; consider compressive/ischaemic causes

Investigations

Goldmann/tonometry (IOP), gonioscopy (open angle), automated visual fields (arcuate/nasal-step defects), optic-disc imaging/OCT, central corneal thickness (pachymetry).

Management

360° selective laser trabeculoplasty (SLT) first-line (NICE 2022); else prostaglandin drops

  1. 1Confirm with IOP, gonioscopy, fields and disc/OCT. If treatment is indicated (IOP ≥24 mmHg with risk of visual impairment), NICE 2022 first-line is 360° SLT.Gate: For people who decline/are unsuitable for SLT, or need additional control, offer a generic prostaglandin analogue; add/switch to beta-blocker, CAI, sympathomimetic or miotic as second-line
  2. 2Inadequate control on laser/drops → trabeculectomy or drainage shunt. Lifelong monitoring of IOP, disc and fields.
Prostaglandin analogue (latanoprost) — first-line drop — increases uveoscleral outflow; lash growth, iris darkening, periocular pigmentation
Topical beta-blocker (timolol) — reduces aqueous production; caution in asthma/heart block
Carbonic anhydrase inhibitor (dorzolamide/brinzolamide) / alpha-agonist (brimonidine) — second-line/adjuncts
Pilocarpine (miotic) — older option; increases trabecular outflow

Key points

Silent peripheral field loss + disc cupping = POAG (found by the optician, not the patient). The 2022 update: SLT, not drops, is first-line. Field loss already lost is irreversible — treatment preserves what remains.

Monitor & prognosis

Lifelong IOP, visual fields and optic-disc/OCT surveillance.

Sight preserved if controlled; established field loss is permanent.

Source: NICE CKS Glaucoma; NICE NG81 (2022)