Snellen Visual Acuity Interpretation
Interprets Snellen chart visual acuity measurements. Standard notation: 6/x metres (UK) or 20/x feet (US). Used to screen for visual impairment, assess driving eligibility, and guide referral to ophthalmology.
Score interpretation
logMAR ≤ 0.30: no distance visual impairment (WHO ICD-11).
→ Routine optometry review (every 2 years). DVLA Group 1 acuity standard is 6/12 binocular with correction if needed (plus the number-plate test).
Worse than 6/12 down to 6/18 (WHO mild). Below the DVLA Group 1 standard if this is the binocular corrected acuity.
→ Optometrist refraction; recheck with correction / pinhole; look for cataract, refractive error or macular disease. Advise not to drive if the binocular corrected acuity is below 6/12.
Worse than 6/18 down to 6/60 (WHO moderate).
→ Ophthalmology referral to find treatable causes (cataract, glaucoma, AMD, diabetic retinopathy); low vision aids; consider sight impairment certification (CVI) if best-corrected and permanent.
Worse than 6/60 down to 3/60 (WHO severe).
→ Ophthalmology referral; certification as sight impaired or severely sight impaired depends on acuity and visual field (CVI); low vision services, social care referral, RNIB signposting.
Worse than 3/60 (WHO blindness).
→ Ophthalmology referral; below 3/60 with a full field meets UK certification as severely sight impaired (CVI); low vision and rehabilitation services.
Interpretation bands for the Snellen Visual Acuity. Apply clinical judgement and local guidance.
References
- Snellen H. Probebuchstaben zur Bestimmung der Sehschärfe. Utrecht: Van de Weijer, 1862.
- World Health Organization. ICD-11 9D90 Vision impairment including blindness (distance categories). 2019.
- DVLA. Assessing fitness to drive: a guide for medical professionals. UK Driver and Vehicle Licensing Agency. 2023.
Related
Curated clinical cross-links plus same-class fallbacks.
- Adult Upper Airway Obstruction (Stridor) · DAS 2015 unanticipated difficult airway; RCEM
- Epistaxis Management · ENT-UK / NICE
- Acute Otitis Media · NICE NG91 2018
- Tonsillitis and Sore Throat · NICE NG84 2018
- Benign Paroxysmal Positional Vertigo · NICE CG124 / AAO-HNS Guidelines
- Acute Rhinosinusitis · NICE NG79 2017 / EPOS 2020
Decision support only — verify against a current formulary, NICE, or your local guideline before clinical use.
