Ishihara Colour Vision Test Interpretation
Pseudoisochromatic plate screening test for congenital red-green colour vision deficiency. Cut-offs depend on the edition (Ishihara instructions). Does not test blue-yellow (tritan) defects. Important for certain occupations (aviation, some transport and clinical roles).
Score interpretation
Plates read correctly at or below the edition's deficiency cut-off.
→ Refer to an optometrist or orthoptist for further classification (e.g. anomaloscope, Farnsworth D-15); advise on implications for occupations that require normal colour vision.
Plates read correctly between the edition's normal and deficiency cut-offs.
→ Repeat under proper daylight-equivalent lighting; further testing (e.g. anomaloscope) via optometry.
Plates read correctly at or above the edition's normal cut-off.
→ No further red-green testing needed; the test does not assess blue-yellow (tritan) defects.
Interpretation bands for the Ishihara Test. Apply clinical judgement and local guidance.
References
- Ishihara S. Tests for Colour-Blindness. 1917. Handaya, Tokyo.
- Cole BL. Assessment of inherited colour vision defects in clinical practice. Clin Exp Optom. 2007;90(3):157–175.
Related
Curated clinical cross-links plus same-class fallbacks.
- Camellia sinensis (sinecatechins) · Topical green tea catechin extract
- Tetracosactide · Synthetic ACTH (short Synacthen test)
- Urea (13C) · 13C-urea breath test
- Indocyanine Green (Intravitreal Chromovitrectomy) · Diagnostic Dye — Vitreoretinal Surgery / ICG Angiography
- Lissamine Green 1% Eye Drops · Vital Dye — Ocular Surface Staining (Dry Eye Diagnosis)
- 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.