---
title: Ishihara test
description: "The [Ishihara test is a widely used colour vision test](https://bluefinvision.com/ishihara-colour-blind-test-online/) made up of plates filled with coloured dots. Hidden numbers or pathways appear in the dots to people with normal colour vision. ## How it works The pattern reveals red-green…"
url: "https://bluefinvision.com/knowledge-base/topics/diagnostics-testing/ishihara-test/"
updated: "2026-01-22"
category: "Diagnostics & Testing"
---

# Ishihara test

The [Ishihara test is a widely used colour vision test](https://bluefinvision.com/ishihara-colour-blind-test-online/) made up of plates filled with coloured dots. Hidden numbers or pathways appear in the dots to people with normal colour vision.

## How it works

The pattern reveals red-green deficiencies.

- Each plate is shown briefly at a comfortable reading distance
- The person names the number or traces the line they can see
- Those with red-green colour blindness may see different figures or none at all
- Scores across several plates indicate whether colour vision is normal or defective

## Uses and limits

The Ishihara test is a screening rather than a full diagnostic tool.

- Primarily detects inherited red-green defects, not all colour problems
- Lighting and familiarity with numbers can influence results
- Abnormal findings can be followed by more detailed colour vision testing
- Often used in school, occupational, and pre‑employment assessments