At Accessibility Summit 2016 conference, accessibility expert Glenda Sims explained what low vision is and how our designs impact people with low vision. Sims offered useful advice for creating universal designs that work for everyone.
Here are my notes and some of the social media discussion, from her presentation.
What is Low Vision?
Low vision refers to visual impairments without blindness. Sims referred to two definitions of low vision. The technical definition: someone with low vision has a visual acuity between 20/70 and 20/200.
Visual acuity refers to sharpness. If you have 20/70 vision, that means you see something at 20 feet from an eye chart that someone with 20/20 vision sees from 70 feet away.
Her second definition of low vision focused on identifying your field of vision and how functional your vision is.
What are the Types of Low Vision?
Low vision includes:
- Color vision
- Field of vision: how much you can see? The center or the edges?
- Light sensitivity: do you dim your display monitor?
- Contrast sensitivity: a common design flaw. Have you tried to read light gray text on a white background?
How Many People are Affected by Low Vision?
According to the World Health Organization, of the 285 million people that are visually impaired, 86 percent of them have low vision. Fourteen percent are blind.
Do the Web Content Accessibility Guidelines 2.0 (WCAG 2.0) Cover Low Vision?
Kind of, but not completely. WCAG 2.0 Level A requires that color alone is not used to convey information.
WCAG 2.0 Level AA has specific requirements for color contrast ratios.
Universal Design Techniques
You may already be using some of these methods to improve your designs for people with low vision. Great! If not, give these recommendations a try:
- Keep text out of images, it causes issues
- Allow users to select background and foreground colors
- For readability, restrict line length to 80 characters for Roman languages, or 40 characters in Asian languages
- Avoid text justification on both left and right sides
- Add sufficient line spacing between lines of text, and between paragraphs
- Avoid horizontal scrolling
https://twitter.com/pfanderson/status/773541074195406850 - Let go of the page context, let content flow
What is the W3C Doing About Low Vision Accessibility?
The W3C Low Vision Task Force has been hard at work, identifying the gap between WCAG 2.0 and what people with low vision need.
A low vision extension to WCAG is in the works, expectations are for the success criteria to be submitted December 15, 2016.
Here’s the list of the low vision categories for user needs:
- Brightness and color
- Ability to track the text
- Ability to see the text
- Perceiving
- Space for reading
- Identification of elements
- Point of regard and proximity
- Working with user settings
Looking for Resources?
- Readability: free web and mobile application that makes reading on the web a better user experience
- A List Apart: How We Read
- Smashing Magazine: Size Matters: Balancing Line Length And Font Size In Responsive Web Design
- No Coffee Chrome extension: vision simulator
Check out some of the conversation on social media during Glenda’s talk:
https://twitter.com/megan_schwarz/status/773553425187352576
https://twitter.com/cyberchucktx/status/773588036391165952
https://twitter.com/redcrew/status/773547504533180416
