Reasoning GP · Algorithm · 1-page summary
Vision loss
For: adults with sudden, transient or gradual loss of vision in primary care — recognise, give first aid, refer. Not for: children, except an absent red reflex (block 2). Local eye-emergency, TIA and stroke pathways take precedence.
Core rule: acute vision loss is an emergency until proven otherwise. Refer via the local eye-emergency, TIA or stroke pathway, start steroid now if GCA is suspected, and never delay transfer for primary-care tests.
0Stop — call 999 now — most eye emergencies are same-day, not 999
- Vision loss with facial droop, dysarthria, weakness, ataxia, reduced consciousness or severe headache; sudden binocular loss with neurological features → 999 stroke assessment.
- Sudden persistent monocular loss (e.g. CRAO) → immediate eye-emergency/stroke pathway; 999 if neurological symptoms, acutely unwell or local transfer rules require.
- Penetrating or severe eye trauma; chemical injury with systemic toxicity, severe bilateral exposure or unable to irrigate safely; instability or unsafe transfer → 999
- While waiting: chemical injury — irrigate now (saline or tap water) before history or acuity, until pH neutral and during transfer; do not patch. No GP tests before transfer.
1Triage by onset — monocular = eye or optic nerve; bilateral = brain
| Onset | Action |
|---|---|
| Sudden, persistent | Same-day eye-emergency / stroke pathway (999 per block 0) |
| Transient, recovered | Suspected TIA → Specialist ≤24 h; aspirin 300 mg (block 5). No ABCD2 downgrade |
| Weeks–months | Optometry/routine; unexplained progressive loss → Urgent ophthalmology |
2Screen — one row is enough
- Over 50 + headache, jaw claudication or tender temporal artery + visual symptoms (GCA) → prednisolone now + Same-day ophthalmology/rheumatology.
- Curtain or shadow, new field defect, shower of floaters, flashes or vitreous haemorrhage → Same-day eye casualty.
- Painful red eye + reduced vision, haloes or abnormal pupil; contact-lens keratitis; anterior uveitis → Same-day ophthalmology.
- Orbital cellulitis (fever, proptosis), optic neuritis → Same-day. Papilloedema → Same-day neurology + imaging.
- Suspected wet AMD (new distortion, central loss) → Macula service ≤1 working day, not 999.
- Child, absent red reflex → consider Urgent ≤2 weeks (NG12); with new squint → refer immediately. Bitemporal hemianopia → Urgent MRI pituitary.
3Assess — only once blocks 0–2 are answered
☐ Acuity each eye, with correction (or CF/HM/PL) ☐ Confrontation fields each eye ☐ Swinging torch (RAPD) ☐ Red desaturation ☐ Fundoscopy ☐ Temporal arteries if over 50 ☐ Cranial nerves III, IV, VI; BP
GCA: CRP, ESR or PV, FBC — never wait for results. Not in primary care: CT head for isolated monocular loss, GP MRI for optic neuritis.
4Classify — only if the screen is negative
- CRAO — sudden painless monocular loss, RAPD, pale retina/cherry-red spot → eye-emergency/stroke pathway; exclude GCA.
- Retinal vein occlusion — retinal haemorrhages → urgent ophthalmology (24–48 h); no anticoagulant or thrombophilia tests.
- Optic neuritis — ache on eye movement, red desaturation, central scotoma → urgent ophthalmology/neurology; specialist MRI.
- AMD — central loss, distortion. Wet → macula service ≤1 working day; dry → optometry.
- Cataract, glaucoma, diabetic retinopathy — gradual, painless → optometry or routine (block 6).
- Uncertain — say so; eye review with a date, and safety-net.
5Treat today — only these
- Suspected GCA: prednisolone now — usually 60 mg with visual symptoms, 40–60 mg without (BSR 2020); gastro- and bone protection by risk.
- Suspected TIA: aspirin 300 mg stat only if TIA likely and no contraindication or significant bleeding risk.
- Not in primary care: topical steroid without slit lamp; glaucoma drops unless ophthalmology directs.
- Doses: NICE/SPC, BNF, local formulary.
6Refer routinely
- Cataract affecting function or quality of life — no fixed acuity threshold (NG77).
- Glaucoma per NG81: disc damage, repeatable field defect or Goldmann IOP ≥24 mmHg.
- Diabetes: DESP annual, or 2-yearly if no retinopathy on two screens; chase non-attenders.
- Hydroxychloroquine: annual retinal monitoring after 5 years (after 1 year if >5 mg/kg/day, eGFR <60 or tamoxifen).
7Never reassure by
- A normal ESR or CRP, or a non-tender temporal artery, in suspected GCA.
- A normal GP fundoscopy or confrontation fields.
- Vision that has fully recovered (amaurosis fugax is a TIA).
- Normal acuity with new flashes and floaters.
- No RAPD (bilateral disease may show none).
- A cup-to-disc ratio or non-contact tonometer reading alone.
8Safety-net — say it, then document it
999 “Call 999 if loss of vision comes with a drooping face, weak arm or leg, slurred speech, unsteadiness, confusion or a severe headache.”
Same-day “Go to the eye emergency service or A&E today for any sudden loss of vision, a curtain or shadow, new flashes or floaters, vision that goes dark then recovers, a painful red eye with blurred vision, or — if over 50 — headache with scalp tenderness or jaw pain on chewing.” Known AMD: new distortion → macula service ≤1 working day.
Driving: not until acuity and fields are assessed; tell DVLA if the standard is not met. Failsafe: confirm urgent referrals were received and attended.
✓Safe to leave primary care only if — all five, documented
No block 0–2 row applies
Acuity each eye, fields, RAPD and fundoscopy recorded
GCA considered if over 50
Optometry, screening or eye referral owner and date set
Safety-net and driving advice documented
Summary of the full Reasoning GP vision loss algorithm, which holds the history, examination, investigations and evidence. Sources: NICE NG128, NG82, NG81, NG77, NG242, NG12 (updated April 2026), QS180; RCOphth emergency eye care, angle closure, retinal vein occlusion and hydroxychloroquine guidance; BSR GCA 2020; NHS Diabetic Eye Screening Programme; DVLA. Clinical reference — follow local eye-emergency, TIA and stroke pathways and check doses: NICE/SPC, BNF.