Blindness

Design considerations

• All content must be present in text or in a text equivalent, because screen readers can't read non-text content.
• All functionality must be available using only a keyboard, because while most blind users can physically move a mouse or trackpad, they can't see where the pointer is.
• Semantic HTML is key, because screen readers offer blind users the ability to navigate by headings, landmarks, and other semantic elements, and also uses those elements to describe what the user is focusing on.
• Custom controls must have the correct name, role, and value, and must change that value when appropriate, so that blind users can understand what is going on.
• Users must receive immediate feedback after all actions, because if the browser is silent, the user doesn't know if what they did had any effect.
• Videos must have audio descriptions if the current audio doesn't describe what's going on in the video -- anything that's purely visual content must be described.
• Touchscreens (primarily on mobile devices) use swipe actions to control the screen reader, so custom swipe actions generally won't work (or will break the screen reader). Similarly, all features require a click action to work.

Source: Deque University accessibility training.

When we design for people with vision impairment we provide:

• The ability to enlarge and reduce text size and images
• The ability to communicate the meaning of visual content - pictures, charts, and icons - through a method other than visual display
• The ability to customize fonts, colors, and spacing
• Properly-tagged semantic HTML understood by a screen reader or text-to-speech software
• Audo descriptions of video in multimedia
• The ability to use a Braille reader
• Forms and data tables where the information is easy to scan and understand even at 400x zoom
• Color palettes and iconography that is compatible with colorblind vision
• Content that always relies on more than just color to communicate meaning
• Keyboard navigation

It's also important to recognize that someone with a visual disability may not know when a new window or browser tab is being opened. Not opening new windows by 30 Days to a More Accessible Website explains more.

What people with blindness say about themselves

• The Things You Don't See by a 21-year-old woman going blind is a blog where she discusses her experiences in life and answers questions on tumblr.
• WebAIM Screen Reader User Survey #7 includes quantitative and qualitative research directly from people using screen readers on how the web is doing (as of 2017)
• What I learned by going blind by Ingrid Ricks on Salon talks about retinitis pigmentosa.
• What It’s Like To Be A Legally Blind Illustrator And Graphic Designer by Keith Rosson at Huffington Post.
• Elsa S. Henry wrote a column on Terrible Minds called So You Wanna Write A Blind Character? that covers what it's like to be blind from a blind person's point of view. Elsa explains how she uses Twitter (reading glasses and Dragon Naturally Speaking), social cues, statistics about blind folks, and guide dogs.
• Alexa is a revelation for the blind by Ian Bogost talks about how, for many blind people, being able to communicate with another human being without someone being a passthrough is a service they may have never had until VUI.
• How the Visually Impaired Experience Hubble Images by NASA is a video of Denna Lambert at the Goddard Space Center describing using this book to learn about telescopes and stars and nebula and planets for the first time.
• Losing my sight made me a better designer by Soren Hamby on Medium

Tools TBD

Additional resources Blindness statistics by the National Federation of the Blind Karwai Pun's Dos and Don'ts on designing for accessibility and the accompanying posters on designing for users of screen readers and designing for users with low vision.