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Understanding Color Blindness & Low Vision

What is Color Blindness?

Understanding color vision deficiency and its global impact

Color blindness, also known as color vision deficiency (CVD), is hereditary. CVD affects how the cone cells in the retina perceive the visible spectrum. The term "color blindness" incorrectly implies that the person can't see color at all. When in fact, most people with CVD can see colors, but have difficulty distinguishing between specific hues, particularly reds and greens or blues and yellows.

8%
of men have some form of color blindness [1,3,4]
0.5%
of women have some form of color blindness [1,3,4]
300M
people worldwide are affected [1,5,8]
99%
of cases are red-green color blindness [1]

Global Distribution

Color blindness prevalence varies by region and ethnicity

1 in 12
men worldwide are colorblind [1,8]
1 in 200
women worldwide are colorblind [1,8]
12
children with CVD born per minute [1]
4.5%
of the world's population [1]

Top Countries by Population

India [1,2]

70 million colorblind people (5.2% of population).

China [1,2,6]

53 million colorblind people (3.7% of population).

United States [1,2]

12 million colorblind people (3.7% of population). 7% of males, 0.4% of females.

Indonesia [1]

11 million colorblind people (4% of population).

Brazil [1]

8 million colorblind people (3.77% of population).

Russia [1]

7 million colorblind people (4.8% of population).

Prevalence by Ethnicity

Northern European Descent [3,4]

Highest rates globally: 7-8% of men, 0.4-0.5% of women affected by red-green color blindness.

East Asian Populations [4,6]

Moderate rates: 4-6.5% of men in Chinese and Japanese populations.

African Descent [4]

Rising prevalence noted in recent surveys, particularly in areas with incoming migration.

Test Your Designs

The Color Blind & Low Vision Simulator is an accessibility tool that allows users to test and observe how people with color blindness or low vision may perceive web-based content.

Download the extension

Simulation Options

  • Protanopia (Red-blind)
  • Deuteranopia (Green-blind)
  • Tritanopia (Blue-blind)
  • Protanomaly (Red-weak)
  • Deuteranomaly (Green-weak)
  • Tritanomaly (Blue-weak)
  • Achromatopsia (No color)
  • Tunnel Vision & More

Types of Color Vision Deficiency

Understanding the different forms and their effects

Protanopia

Complete absence of red cone cells. Red appears as dark grey or black, and certain shades of orange, yellow, and green all appear as yellow.

Deuteranopia

Complete absence of green cone cells. The most common form, causing difficulty distinguishing between red, green, brown, and orange.

Tritanopia

Rare condition with absence of blue cone cells. Blue appears green, and yellow appears violet or light grey.

Protanomaly

Reduced sensitivity to red light. Red, orange, and yellow appear greener, and colors are not as bright.

Deuteranomaly

The most common type overall. Reduced sensitivity to green light, making green and yellow appear redder.

Tritanomaly

Extremely rare. Reduced sensitivity to blue light, causing difficulty distinguishing blue from green and yellow from violet.

Design for Color Blindness

Best practices for designing inclusive digital experiences for everyone

Use Patterns & Textures

Add patterns, textures, or hatching to distinguish elements beyond color alone in charts and data visualizations.

Sufficient Contrast

Maintain a minimum 4.5:1 contrast ratio for normal text and 3:1 for large text and UI components.

Icons & Labels

Combine color with icons, text labels, or other visual indicators to convey information.

Test Your Designs

Use color blindness simulators and automated tools to verify your design works for all users.

Avoid Problematic Pairs

Be cautious with red-green, blue-yellow, green-brown, and blue-purple combinations without additional differentiation.

Underline Links

Don't rely solely on color to indicate links. Use underlines or other visual cues to make them identifiable.

Web Accessibility

The Web Content Accessibility Guidelines (WCAG) and the World Wide Web Consortium (W3C) resources for color accessibility

The WCAG and related W3C resources provide guidance on creating accessible web experiences for people with color vision deficiency

1

WCAG 2.2 - Use of Color

Success Criterion 1.4.1: Color is not used as the only visual means of conveying information

2

WCAG 2.2 - Contrast (Minimum)

Success Criterion 1.4.3: Minimum contrast ratio of 4.5:1 for normal text

3

WCAG 2.2 - Contrast (Enhanced)

Success Criterion 1.4.6: Enhanced contrast ratio of 7:1 for normal text (Level AAA)

4

W3C Color Contrast Guidance

Web accessibility guidelines for color contrast to support low vision users

5

Technique G182: Additional Visual Cues

Ensuring additional visual cues are available when text color is used to convey information

6

Technique G183: Using 3:1 Contrast for Surrounding Context

Using a contrast ratio of 3:1 with surrounding text and providing additional cues

7

Accessibility Requirements for Low Vision

W3C documentation on color-related needs for people with low vision

8

CSS Color Module Level 4

Technical specification for color representation in CSS

Understanding Low Vision

Visual impairment that affects millions globally

Low vision is a visual impairment that can't be corrected with standard glasses, contact lenses, medication, or surgery, and significantly interferes with daily activities. Unlike total blindness, individuals with low vision retain some usable vision. According to the World Health Organization, there are at least 2.2 billion people worldwide who have some form of vision impairment[9,10], with approximately 295 million experiencing moderate to severe vision impairment and 43 million living with blindness[10,11]. The prevalence of vision impairment increases significantly with age, and it is estimated that by 2050, over 1.8 billion people will be affected by some form of vision loss[12].

2.2B
people worldwide have some form of vision impairment [9,10]
295M
people have moderate to severe vision impairment [10,11]
43M
people are blind globally [10,11]
80%
of vision impairment is preventable or treatable [9,13]
1.8B
projected to have vision loss by 2050 [12]
55%
of people with vision impairment are women [12]
90%
of people with vision impairment live in low and middle-income countries [12]
$411B
annual global productivity loss due to vision impairment [9]

Types of Low Vision

Common visual impairment categories and conditions

Central Vision Loss

Inability to see things in the center of vision, often caused by age-related macular degeneration (AMD) or Stargardt disease. Affects reading and recognizing faces.

Peripheral Vision Loss

Difficulty seeing objects in the corners of eyes, commonly caused by glaucoma or retinitis pigmentosa. Results in tunnel vision and mobility challenges.

Night Blindness

Reduced ability to see in low light conditions, often associated with retinitis pigmentosa or vitamin A deficiency. Makes navigation in dim environments difficult.

Cataracts

Clouding of the eye's natural lens causing blurred vision and glare sensitivity. The leading cause of preventable blindness worldwide, affecting over 94 million people[14].

Diabetic Retinopathy

Damage to retinal blood vessels from diabetes. Affects 3.9 million people with vision impairment[15], causing blurred vision, floaters, and potential blindness.

Glaucoma

Optic nerve damage from eye pressure. Affects over 80 million people worldwide[10], causing peripheral vision loss and reduced contrast sensitivity.

Age-Related Macular Degeneration

Progressive deterioration of the macula affecting central vision. Leading cause of vision loss in people over 65, impacting 8 million people globally[16].

Retinitis Pigmentosa

Inherited condition causing gradual vision loss. Affects rod cells first, leading to night blindness and progressive tunnel vision over time.

Uncorrected Refractive Errors

Myopia, hyperopia, and astigmatism that cannot be corrected. Affects 88.4 million people[10], causing blurred vision at various distances.

Design for Low Vision

Best practices for designing experiences for users with low vision

Contrast

Maintain minimum 4.5:1 contrast ratio for normal text and 3:1 for large text. Use high contrast color combinations and avoid light text on light backgrounds.

Scalable Text

Use relative units (em, rem) instead of fixed pixels. Ensure text can be resized up to 200% without loss of content or functionality.

Clear Typography

Use sans-serif fonts with adequate spacing. Minimum 16px base font size, 1.5 line height, and avoid italic or condensed fonts for body text.

Zoom & Magnification

Support browser zoom without horizontal scrolling. Ensure layouts reflow properly and information remains visible when magnified.

Don't Relying on Color Alone

Combine color with text labels, icons, patterns, or textures. This helps users with both color blindness and low vision understand information.

Keyboard Navigation

Ensure all interactive elements are keyboard accessible with visible focus indicators.

Touch Targets

An ideal target is no less than 44x44 pixels, however, the minimum is 24x24 pixels for touch targets with adequate spacing. Larger targets are easier to see and interact with for low vision users.

Motion & Animation

Avoid excessive animations, parallax effects, and flashing content. For animation / movement lasting longer than three seconds, provide controls to pause or reduce motion.

Screen Reader Compatibility

Use semantic HTML and ARIA labels properly. Many low vision users combine screen magnification with screen readers.

Low Vision Resources

Information for understanding low vision

1

WHO Vision Impairment Fact Sheet

Official statistics on global visual impairment and blindness from the World Health Organization

2

National Eye Institute - Low Vision

Comprehensive information on low vision types, causes, and treatments

3

W3C Color Contrast Guidance

Web accessibility guidelines for color contrast to support low vision users

4

W3C Low Vision Accessibility Task Force

Technical specifications and best practices for low vision accessibility

5

WebAIM - Visual Disabilities

Detailed guide on designing for various types of visual disabilities

6

VisionAware

Practical resources for adults experiencing vision loss

Statistical References

Sources for color blindness and low vision data

1

Colorblind People Population Statistics

Global prevalence data including 1 in 12 men, 1 in 200 women, and country-specific populations

2

Color Blindness Statistics by Country

Comprehensive data on affected populations in India, China, United States, and other nations

3

Global Perspective of Color Vision Deficiency - PMC

Peer-reviewed research on prevalence by ethnicity including Northern European populations (8% males, 0.5% females)

4

Worldwide Prevalence of Red-Green Color Deficiency - PubMed

Research on ethnic variations: 8% European Caucasian men, 4-6.5% East Asian men, and African populations

5

Color Blind Statistics and Facts - Vision Center

Data on 300 million affected individuals worldwide and regional distribution patterns

6

Color Blindness Statistics (2025)

China 6.9% males/0.5% females (3.7% total), Japan 5% males/0.2% females, 107 million in China

7

Global Prevalence Meta-Analysis - ARVO Journals

Systematic review showing CVD prevalence varies from 1.40% to 13.93% across 16 countries

8

What Percent of the Population is Color Blind?

Overview of 8% male/0.5% female prevalence and 300+ million global population estimate

9

WHO Blindness and Visual Impairment Fact Sheet

2.2 billion people with vision impairment, 80% preventable/treatable, $411B annual productivity loss

10

Global Burden of Disease Study - Vision Loss

Comprehensive data on 295M with moderate to severe vision impairment, 43M blind, leading causes including cataracts (94M), refractive error (88.4M), glaucoma (7.7M)

11

WHO World Report on Vision

At least 2.2 billion people have vision impairment, with at least 1 billion cases preventable or yet to be addressed

12

Global Vision Loss Projections to 2050

1.8 billion projected by 2050, 55% women, 90% in low and middle-income countries, aging population and lifestyle factors

13

Blindness - StatPearls - NCBI

80% of visual impairments worldwide can be prevented, treated, or cured with proper eye care

14

Global Estimates on Cataract - PubMed

94 million people with vision impairment due to cataract globally from 2000-2020

15

Diabetic Retinopathy Vision Impairment - PMC

3.9 million people with vision impairment, 1.07 million blind due to diabetic retinopathy in 2020

16

Age-Related Macular Degeneration Burden - PMC

8 million people with vision loss due to AMD, projected to exceed 9 million by 2050