Reasoning GP · Algorithm · 1-page summary
Blurry or reduced vision
For: adults with new or worsening blurred or reduced vision, including diplopia, face to face or remote. Not for: children, except an absent red reflex (block 2); eye injury beyond first aid goes to the eye emergency service.
Core rule: sudden visual loss is an emergency until proven otherwise. Cover each eye, check acuity with a pinhole, and never delay transfer for GP tests, treatment or a normal fundoscopy.
0Stop — call 999 now — most eye emergencies are same-day, not 999
- Sudden visual loss with stroke features (facial weakness, slurred speech), reduced consciousness or focal neurology → 999 (thrombolysis window).
- Painful red eye or angle closure with collapse, marked vomiting, confusion or systemic illness; orbital cellulitis with visual loss, proptosis or toxicity → 999
- Pregnancy: visual symptoms with eclampsia or severe hypertension; chemical injury needing ongoing irrigation; anyone unable to transfer safely → 999
- While waiting: chemical injury — irrigate now with water or saline, remove lenses if easy, continue during transfer until pH neutral; no neutralising chemicals. Do not delay transfer for GP tests.
1Triage by onset — monocular = eye; binocular = brain
| Onset | Action |
|---|---|
| Sudden, persistent | Same-day eye emergency / stroke pathway |
| Transient, recovered | Suspected TIA → Specialist ≤24 h; aspirin 300 mg if no contraindication. Over 50: think GCA |
| Days–weeks | Unexplained progressive loss or uveitis → Same-day |
| Months–years | Pinhole improves → optometrist; else block 4 |
2Screen — one row is enough
- Curtain, field loss, or flashes/floaters with reduced vision → Same-day. Flashes/floaters alone → Dilated exam ≤24 h
- Painful red eye, reduced vision, haloes (angle closure) → Same-day eye casualty. No dilating drops; drugs and positioning as the eye team advises.
- Over 50, headache, scalp tenderness, jaw claudication + visual symptoms (GCA) → steroid now + Same-day assessment.
- Sudden painless monocular loss, including in diabetes → Same-day eye emergency / stroke pathway.
- New diplopia with dilated pupil (3rd nerve), severe headache, neuro signs or proptosis; papilloedema → Same-day
- Suspected wet AMD (new distortion, grey central patch) → Macula service ≤1 working day. Child, absent red reflex → consider Urgent ≤2 weeks (NG12)
3Assess — only once blocks 0–2 are answered
☐ Acuity each eye, with glasses and pinhole ☐ Pupils, swinging torch (RAPD) ☐ Confrontation fields ☐ Eye movements ☐ Red eye, proptosis ☐ Fundoscopy (disc, macula)
GCA: FBC, ESR, CRP alongside treatment. Not in primary care: CT head for pinhole-correctable blur.
4Classify — only if the screen is negative
- Refractive error or cataract — gradual, painless; glare, haloes → optometrist.
- Dry eye — fluctuating, improves with blinking, gritty → lubricants. Not if painful, red and vision reduced.
- AMD — central loss, distortion. Dry → optometry review; wet → macula service ≤1 working day.
- Glaucoma, diabetic retinopathy — often silent; found by optometry or retinal screening. GPs do not re-grade images.
- Optic neuritis — subacute, pain on eye movement, red desaturation, RAPD → urgent ophthalmology or neurology; no GP steroids.
- Uncertain — say so; eye review with a date, and safety-net.
5Treat today — only these
- Suspected GCA: prednisolone now per local pathway (BSR: 40–60 mg; visual loss commonly 60 mg); IV methylprednisolone is specialist-led.
- Dry eye: hypromellose 0.3% 4–6 times daily ± carbomer gel at night; preservative-free if used often.
- Vascular causes: BP, HbA1c, lipids, smoking, AF — never delaying eye referral. No antiplatelet or anticoagulant for unexplained visual disturbance alone.
- Doses: NICE/SPC, BNF, local formulary.
6Refer routinely
- Gradual bilateral blur, mild dry eye, stable mild cataract → optometrist first.
- Routine ophthalmology: cataract with functional impairment; suspicious disc, repeatable field defect or Goldmann IOP ≥24 mmHg (NG81); stable dry AMD.
- Urgent ophthalmology: retinal vein occlusion, new proptosis, isolated stable diplopia. Neurology: bitemporal hemianopia, fatigable ptosis.
- Hydroxychloroquine: hospital retinal monitoring yearly after 5 years (after 1 year if eGFR <60, tamoxifen or >5 mg/kg/day).
7Never reassure by
- A normal GP fundoscopy or confrontation fields.
- Normal ESR or CRP in suspected GCA.
- Blurring that has fully recovered (possible TIA).
- A diabetes label: sudden loss is not automatically a bleed.
- Calling a painful red eye with reduced vision "dry eye".
- A single non-contact tonometer reading.
8Safety-net — say it, then document it
999 “Call 999 if you lose vision with a drooping face, weak arm, slurred speech, confusion, collapse or feeling very ill.”
Same-day “Go to the eye emergency service today for any sudden loss of vision, a curtain or shadow, new flashes and floaters, a painful red eye with cloudy vision, vision that dims then recovers, new double vision, or — if over 50 — headache with scalp tenderness or jaw pain on chewing.” Known AMD: new distortion or central blur → macula service ≤1 working day.
✓Safe to leave primary care only if — all five, documented
No block 0–2 row applies
Acuity each eye with pinhole, pupils and fields recorded
One cause explains it, or uncertainty stated
Optometry, screening or eye referral owner and date set
Safety-net given and documented
Summary of the full Reasoning GP blurry vision algorithm, which holds the detail, examination, investigations and evidence. Sources: NICE NG82, NG81, NG128, TA518, NG12 (updated April 2026); RCOphth angle closure, retinal artery occlusion and hydroxychloroquine guidance; BSR GCA 2020; College of Optometrists; NHS Diabetic Eye Screening Programme. Clinical reference — follow local eye emergency, macula and stroke pathways and check doses: NICE/SPC, BNF.