What is Color Blindness?
Color blindness (color vision deficiency) affects ~8% of men and ~0.5% of women. It is usually genetic, caused by absent or defective cone photoreceptors in the retina. Most people with color blindness see color — just differently.
Types of Color Vision Deficiency
Deuteranopia (most common): Missing M-cones (green-sensitive). Red and green appear similar — olive-yellow-ish. Protanopia: Missing L-cones (red-sensitive). Red appears very dark/black. Tritanopia (rare): Missing S-cones (blue-sensitive). Blue/yellow confusion. Achromatopsia: Complete monochromacy — sees only shades of grey (extremely rare).
Designing for Color Accessibility
Never use color as the only way to convey information. Pair color with icons, patterns, or text labels. Use high-contrast ratios (WCAG AA requires 4.5:1 for normal text). Test palettes with our color blindness simulator. Avoid red/green combinations for critical UI states (success/error). Blue is the safest accent color — visible to all deficiency types.
WCAG Color Contrast Requirements
WCAG 2.1 Level AA requires: 4.5:1 contrast ratio for normal text (<18pt). 3:1 for large text (18pt+ or 14pt bold). 3:1 for UI components and graphical objects. Level AAA requires 7:1 for normal text. Use our contrast checker to verify compliance.