Imagine that every interface you design is seen by 350 million people who cannot access the information you're conveying through color. Not because they don't have a screen. Not because they're not looking. Simply because their visual system works differently from yours.
That is the daily reality of color blindness.
What "seeing colors differently" actually means
Color vision relies on three types of photoreceptors in the retina — the cones — which capture different wavelengths of light. When one or more types of cones are absent or functioning abnormally, color perception changes. Three main cases:
Monochromacy: total absence of cones. No color perceived — only grayscale. Rare, but real.
Dichromacy: absence of one type of cone. Inability to distinguish reds from greens (protanopia, deuteranopia) or blues from yellows (tritanopia).
Anomalous trichromacy: all three cone types present, but one responds to a shifted wavelength. Color is perceived, but with insufficient intensity.
The numbers that should move things
8% of men and 0.5% of women have a color vision deficiency.
98% of cases involve red-green confusion.
350 million people worldwide are affected.
Aging compounds the issue independently of any color blindness: contrast sensitivity declines with age. Your audience is aging. Your interface had better account for it.
This is not an edge case. This is your audience.
The digital problem in 2025
And here's where it gets uncomfortable: 79.1% of tested homepages fail the minimum contrast criterion defined by the WCAG. Contrast error is by far the most common accessibility failure on the web. In 2024, an average of 56.8 accessibility errors per homepage were recorded — 13.6% more than in 2023. In total, 96.3% of websites still don't meet basic accessibility standards.
This is not a niche problem. It's a silent epidemic — visible to 350 million people.
And now it's the law
Since June 28, 2025, EU Directive 2019/882 has entered into force. Covered private-sector companies must now ensure their digital services comply with standard EN 301 549, directly derived from WCAG 2.1 Level AA. In France, the RGAA has imposed similar obligations on the public sector for years.
This is no longer an optional best practice. It's a legal obligation with available recourse.
The baseline rule: color alone ≠ information
An error message in red, a status indicator in green, a greyed-out disabled button — if color is the only signal, a significant portion of your users misses it. The rule is simple: always pair color-based information with another signal — icon, text, texture, pattern, position.
And test. Free, effective tools exist: axe DevTools, Lighthouse, Colour Contrast Analyser, or the color vision deficiency simulators built into Chrome DevTools (Rendering → Emulate vision deficiencies).
What this means for your role
Designers: integrate WCAG contrast ratios from the mockup phase. Never rely on color as the sole information carrier. Test hover, focus, and disabled states.
Devs: audit with axe or Lighthouse before every PR, document color design tokens with their contrast ratios. UI components must be accessible by default — not patched at the end of the sprint.
HR and recruiters evaluating portfolio projects: a solid front-end project passes accessibility tests. It's a signal of seniority, not a bonus.
One last fact for the skeptics: in 2023, the US Department of Justice fined several companies for digital accessibility non-compliance. The momentum is arriving in Europe. The question is no longer "should we" — it's "are we ready."