Visual impairments

Color vision deficiency

("Color blindness")

Color vision deficiencies are anomalies in wavelength sensitivity or absence of photoreceptor cells. Approximately 8% of males and 0.5% of females have a color vision deficiency.

Three plates from the Ishihara color test with hidden numbers 12, 74, and 45 Three plates from the Ishihara color test with hidden numbers 12, 74, and 45

Types of color vision deficiency include:

How it affects UI design

Designing with color vision deficiencies in mind is important. Most issues can be resolved by compliance with WCAG 1.4.1 (use of color) and 1.4.3 (contrast minimum).

When color identification is important to all sighted users, use a color tool to evaluate color difference for each color deficiency type.

Sources:

  1. Thomas Norton, David Corliss, James Bailey (2020). The Psychophysical Measurement of Visual Function. 1st edition. Butterworth-Heinemann. Pages 268-269
  2. Daniel Flück. Colblindor. https://www.color-blindness.com/ishiharas-test-for-colour-deficiency-38-plates-edition/
  3. Success Criterion 1.4.1 Use of Color. Web Content Accessibility Guidelines (WCAG) 2.1. https://www.w3.org/TR/WCAG21/#use-of-color
  4. Success Criterion 1.4.3 Contrast (Minimum). Web Content Accessibility Guidelines (WCAG) 2.1. https://www.w3.org/TR/WCAG21/#contrast-minimum