---
title: Colour blind test
description: "A [colour blind test](https://bluefinvision.com/ishihara-colour-blind-test-online/) assesses how well someone can distinguish different colours, usually to detect red-green colour vision deficiencies. Many people are born with mild defects and may not notice problems until tested. ## Types of testing Simple screening can…"
url: "https://bluefinvision.com/knowledge-base/topics/diagnostics-testing/colour-blind-test/"
updated: "2026-01-22"
category: "Diagnostics & Testing"
---

# Colour blind test

A [colour blind test](https://bluefinvision.com/ishihara-colour-blind-test-online/) assesses how well someone can distinguish different colours, usually to detect red-green colour vision deficiencies. Many people are born with mild defects and may not notice problems until tested.

## Types of testing

Simple screening can be done quickly in clinic.

- Plate tests present numbers or shapes made of coloured dots
- People with colour deficiency may not see some figures correctly
- More detailed tests can grade the severity and type of defect
- Some occupational assessments use tailored colour vision standards

## Practical implications

Most colour vision defects are stable and cannot be cured.

- Important for career guidance in jobs that rely on accurate colour discrimination
- Helps explain difficulties with traffic lights, wiring, or colour‑coded charts
- Children with suspected problems should be tested early
- Changes later in life can signal retinal or optic nerve disease and need specialist review