Vision disabilities affect how people perceive and interact with visual content on the web. Understanding these disabilities is essential for creating accessible digital experiences that work for everyone. This guide explores the spectrum of vision-related disabilities, from complete blindness to color vision deficiencies, and explains how each impacts web use.
Vision disabilities are among the most common disabilities worldwide, affecting hundreds of millions of people. By designing with vision accessibility in mind, we create better experiences not just for people with disabilities, but for all users in various situations—from bright sunlight that makes screens hard to see, to temporary vision problems from eye strain or medical procedures.
Types of Vision Disabilities
Vision disabilities exist on a broad spectrum, including:
- Blindness - Complete or near-complete loss of vision
- Low vision - Partial vision loss that can’t be fully corrected
- Color blindness - Difficulty distinguishing certain colors
- Light sensitivity - Difficulty with bright lights or certain color combinations
Each type of vision disability requires different accommodations and assistive technologies to access web content effectively.
Blindness
According to the CDC, approximately 1 million people in the United States are blind. Globally, an estimated 39 million people are blind, with many more experiencing severe vision impairment.
People who are blind cannot see visual content, making it essential that all information is available through non-visual means. This includes providing text alternatives for images, ensuring proper semantic structure, and making interactive elements keyboard-accessible.
How People Who Are Blind Use the Web
Screen readers: Screen readers convert digital text into synthesized speech or refreshable braille displays. Popular screen readers include:
- JAWS (Job Access With Speech)
- NVDA (NonVisual Desktop Access)
- VoiceOver (macOS and iOS)
- TalkBack (Android)
- Narrator (Windows)
Navigation methods: Screen reader users navigate websites differently than sighted users:
- Headings: Jump between heading levels to understand page structure
- Landmarks: Navigate by regions like navigation, main content, and footer
- Links: List all links to find specific destinations quickly
- Form fields: Tab through interactive elements
- Tables: Navigate by rows and columns to understand data relationships
Design Considerations for Blindness
Provide text alternatives: All images, charts, graphs, and visual content must have descriptive text alternatives that convey the same information.
Use semantic HTML: Proper heading structure, landmarks, and semantic elements help screen readers understand and communicate page structure.
Ensure keyboard accessibility: All functionality must be available using only a keyboard, as screen reader users typically don’t use a mouse.
Label interactive elements: All buttons, form fields, and controls need clear, descriptive labels that explain their purpose.
Provide context: Information cannot rely solely on visual cues like color, position, or highlighting. Provide explicit text descriptions.
Structure custom controls properly: When creating custom widgets like accordions, dialogs, or media players, use appropriate ARIA roles, states, and properties to communicate functionality to screen readers.
Low Vision
Low vision is a broad category encompassing many conditions with varying degrees of visual impairment. People with low vision have partial sight that cannot be fully corrected with glasses, contact lenses, or surgery.
Approximately 246 million people worldwide have low vision. The causes and effects vary widely, making it important to understand different low vision conditions and their impacts.
Types of Low Vision Conditions
Blurred vision: Faces and objects appear out of focus, making it difficult to distinguish features, read text, or perceive fine details.
Low contrast sensitivity: Difficulty seeing elements that don’t have strong contrast differences. This makes it hard to distinguish:
- Outlines and borders
- Edges between objects
- Subtle details
- Light text on light backgrounds or dark text on dark backgrounds
Cataracts: Clouding of the eye’s lens creates a foggy or hazy appearance. People with cataracts may see:
- Clouded or dimmed vision
- Halos around lights
- Faded colors
- Double vision in one eye
Retinal detachment: Separation of the retina from the back of the eye can cause:
- Sudden flashes of light
- Floaters (spots or threads in vision)
- Dark shadows covering portions of the visual field
- Curtain-like effect across vision
Diabetic retinopathy: Damage to retinal blood vessels from diabetes causes:
- Dark spots or floaters
- Blurred or fluctuating vision
- Dark or empty areas in vision
- Difficulty with color perception
Glaucoma: Increased eye pressure damages the optic nerve, resulting in:
- Loss of peripheral vision (tunnel vision)
- Seeing only a small central area
- Heavily darkened edges of vision
- Progressive vision loss if untreated
Hemianopia: Loss of vision in half the visual field (left or right side) in both eyes, caused by brain injury or stroke.
Macular degeneration: Deterioration of the central retina (macula) causes:
- Blurred central vision
- Blind spot in central vision
- Difficulty recognizing faces
- Straight lines appearing wavy or distorted
- Preserved peripheral vision
Assistive Technologies for Low Vision
Screen magnifiers: Software and hardware that enlarge portions of the screen for easier viewing:
- ZoomText - Windows magnification software with enhancement options
- MAGic - Screen magnification with optional screen reader
- Built-in magnifiers - Operating system zoom features (Windows Magnifier, macOS Zoom)
- Browser zoom - Enlarging web page content
Screen magnifiers with enhancement: Advanced magnifiers offer:
- High-resolution magnification
- Color enhancement and inversion
- Pointer and cursor enlargement
- Focus highlighting
- Customizable color schemes
Screen readers: Many people with low vision use screen readers alongside visual reading to:
- Confirm what they’re seeing
- Reduce eye strain
- Access content more efficiently
- Supplement partial vision with audio
Note: Screen magnification tools often include basic screen reader features, but dedicated screen readers like JAWS and NVDA offer more comprehensive functionality.
Design Considerations for Low Vision
Provide sufficient contrast: Ensure text and interactive elements have at least 4.5:1 contrast ratio with backgrounds (3:1 for large text).
Support text resizing: Design layouts that work when users increase text size up to 200% without loss of content or functionality.
Avoid small text: Use readable font sizes (minimum 16px for body text recommended).
Create clear visual hierarchy: Use spacing, sizing, and contrast to make content structure obvious.
Provide focus indicators: Make keyboard focus clearly visible with strong contrast and sufficient size.
Allow customization: Don’t prevent users from overriding colors, increasing text size, or adjusting spacing.
Avoid low contrast: Don’t rely on subtle shading or light gray text to convey information.
Consider color schemes: Provide high-contrast modes or respect user operating system preferences.
Color Blindness
Approximately 300 million people worldwide have color vision deficiency. It affects roughly 1 in 12 men (8%) and 1 in 200 women (0.5%). Color blindness is much more common in males due to genetic factors.
Color blindness doesn’t mean seeing no color at all (though this is possible in rare cases). It means having difficulty distinguishing between certain colors, particularly in the red-green or blue-yellow spectrum.
Types of Color Blindness
Red-green color blindness (most common): Difficulty distinguishing between reds, oranges, yellows, greens, and browns.
- Deuteranopia - Green-blindness (most common type)
- Protanopia - Red-blindness
- Deuteranomaly - Reduced sensitivity to green light
- Protanomaly - Reduced sensitivity to red light
Blue-yellow color blindness (less common):
- Tritanopia - Blue-blindness
- Tritanomaly - Reduced sensitivity to blue light
Difficulty distinguishing between blues, greens, yellows, and violets.
Complete color blindness (very rare):
- Achromatopsia - Complete inability to see color (grayscale vision)
- Achromatomaly - Partial color blindness affecting all colors
Red-black confusion: Some people confuse dark red with black, making certain color combinations problematic.
Common Problem Color Combinations
People with color blindness often struggle to distinguish:
- Red and green
- Red and brown
- Red and orange
- Green and brown
- Green and yellow
- Blue and purple
- Pink and gray
Design Considerations for Color Blindness
Never use color alone to convey information: This is the most critical principle. Always provide additional cues beyond color:
<!-- Bad: Color only -->
<span style="color: red;">Error</span>
<span style="color: green;">Success</span>
<!-- Good: Color plus icon and text -->
<span class="error">
<svg aria-hidden="true"><!-- error icon --></svg>
Error: Invalid email format
</span>
<span class="success">
<svg aria-hidden="true"><!-- success icon --></svg>
Success: Form submitted
</span>Use patterns and textures: In charts and graphs, combine color with patterns, shapes, or labels to distinguish elements.
Provide text labels: Label chart elements, form validation messages, and status indicators with text, not just color.
Choose accessible color palettes: Use color combinations that work for color-blind users:
- Blue and orange (instead of red and green)
- Use sufficient contrast between colors
- Test with color blindness simulators
Include icons and symbols: Use icons alongside color to indicate status, categories, or actions:
- ✓ for success (not just green)
- ✗ for errors (not just red)
- ⚠ for warnings (not just yellow)
Underline links: Don’t rely on color alone to distinguish links from regular text. Use underlines or other visual indicators.
Test your designs: Use color blindness simulation tools to see how your design appears to users with different types of color vision deficiency.
Color Blindness Testing Tools
- Coblis - Color Blindness Simulator
- Color Oracle - Free color blindness simulator for Windows, Mac, and Linux
- Browser DevTools - Chrome and Firefox include color blindness emulation
- Stark - Design plugin for Figma, Sketch, and Adobe XD
Overlapping Needs and Considerations
Many accessibility features benefit multiple groups:
High contrast helps:
- People with low vision
- People with color blindness
- People viewing screens in bright sunlight
- People with aging vision
Clear, simple language helps:
- People using screen readers
- People with cognitive disabilities
- Non-native language speakers
- Everyone who wants quick, clear information
Keyboard accessibility helps:
- People who are blind
- People with motor disabilities
- Power users who prefer keyboards
- People whose pointing devices aren’t working
Flexible layouts help:
- People who magnify content
- People using mobile devices
- People with different screen sizes
- Everyone accessing content in various contexts
Conclusion
Vision disabilities are diverse and affect millions of people worldwide. By understanding these disabilities and designing with them in mind, we create websites and applications that are accessible to everyone.
Key principles for vision accessibility:
- Provide text alternatives for all visual content
- Ensure sufficient color contrast (4.5:1 minimum for text)
- Never rely on color alone to convey information
- Use semantic HTML and proper structure
- Support keyboard navigation completely
- Allow text resizing without loss of functionality
- Label all interactive elements clearly
- Test with assistive technologies and simulation tools
Remember: Accessible design isn’t just about compliance—it’s about creating inclusive experiences that work for all users, regardless of how they perceive and interact with visual content. The accommodations we make for vision disabilities often benefit everyone, creating clearer, more usable websites for all.
When we design with vision accessibility in mind from the start, we build better products that serve a wider audience. That’s not just good accessibility practice—it’s good design.
Resources
Screen readers:
- JAWS - jaws-download
- NVDA - nvaccess.org
- VoiceOver - Built into macOS and iOS
- TalkBack - Built into Android
Testing tools:
- WAVE - Web accessibility evaluation tool
- axe DevTools - Browser extension for accessibility testing
- Color contrast analyzers
- Color blindness simulators
Guidelines:
- WCAG 2.1 - Web Content Accessibility Guidelines
- Section 508 - US federal accessibility requirements
- Understanding vision disabilities - W3C accessibility fundamentals