Color Blindness (CVD) and Multi-Signal Accessibility

Approximately 8% of men and 0.5% of women worldwide experience Color Vision Deficiency (CVD):

• Protanopia & Deuteranopia (Red-Green Deficiencies): The most common forms; users cannot differentiate between red and green.
• Tritanopia (Blue-Yellow Deficiency): Rarest form; difficulty distinguishing blue from green and yellow from violet.
• Achromatopsia: Complete color blindness; seeing entirely in grayscale.

The Multi-Signal Mandate (WCAG 1.4.1)

Never use color as the sole visual signifier of status or interactivity:

• Success messages must include a checkmark icon and text confirmation alongside green styling.
• Error alerts must include an alert icon and descriptive copy alongside red outlines.