Web accessibility for low vision and blindness

Visual disabilities are among the most common disabilities. According to the World Health Organization, vision disabilities affect up to 2.2 billion people worldwide. How do people with blindness or low vision access the internet?

For individuals with visual impairments, there are many options and tools to choose from when it comes to unlocking the visual aspects of the internet. Understanding these options can help developers and content creators be more aware as they develop online content. As a bonus, many accessibility guidelines increase a site’s search engine optimization.

This article will provide an overview of various options and tools people with blindness or low vision use to access websites. Each section describes:

• What is the tool and how does it work?
• Who uses the tool?
• Web Content Accessibility Guidelines that help make the tools work

Screen reading software

What is screen reading software and who uses it?

Screen reading software is precisely what it sounds like. Software like Job Access With Speech (JAWS) or NonVisual Desktop Access (NVDA) turns visual elements into speech. These readers are not just simple text-to-speech; they also support navigation and comprehension of  buttons or images.

People with no usable vision primarily use screen readers. Some people with low vision might also use it in combination with their eyes or only some of the time.

How do you make your content screen reader ready?

For someone using a screen reader to be able to use your website:

• All images must have text alternatives (see WCAG guideline 1.1.1 Non-text Content Level A) 
• Audio content must not interfere (see WCAG guideline 1.4.2 Audio Control Level A) 
• It must be possible to navigate your website with only a keyboard (see WCAG guideline 2.1 - keyboard accessible) 
• Your website must use navigation elements like headings, lists and descriptive links (see WCAG guideline 2.4 - navigable) 

The “why” behind the first two bullets is probably self-explanatory. The software can’t read anything that isn’t text; it will only state an image exists. If audio exists, it should not autoplay. A person can’t listen to their screen reader if there’s an audio file playing simultaneously. 

To explain the other two bullets, let's look at how to navigate a website if it is not visible. 

Navigation using a screen reader

If someone cannot see a screen, they cannot use a mouse to navigate the site. It must be possible for someone to use their tab and arrow keys to get around the area. This means the focus order of the site must follow a logical order. 

Properly nested headings, defined lists and descriptive links are important. They allow screen reader users to skip to different parts of the page. When sighted users go to a webpage, they don’t always start at the beginning and read through everything - they might skip to what matters to them. Screen reader users deserve to be able to do the same thing. Software like JAWS has built-in keyboard shortcuts the user can press to hear a list of the page’s headings, lists or links. 

Online content likely already includes headings, but it is important to make headings in a way that is usable by a screen reader. A screen reader can’t identify that as a headings based on text styles and font sizes. In HTML, this means using heading tags like H1 or H2. You can still use font style and size, you just can’t rely on those features alone.

Descriptive links are also important. Imagine using a keyboard shortcut to hear a list of the links on a page and then hearing “click here” repeatedly. Attaching links to text that explains where they will direct a reader is helpful for screen readers and search engine optimization.

Refreshable braille

Anyone who knows braille might use a refreshable braille display. These devices convert text into braille, refreshing as they go. People might use refreshable braille because of:

• Personal preference
• Current setting
• Other disabilities, particularly deafness.

The good news is that refreshable braille depends on the same accessibility features as a screen reader. So once you make your content accessible for a screen reader, you’re already most of the way there. Site owners need to ensure that people who are deaf and blind can access the auditory elements on your webpage in addition to the visual elements 

Zooming and magnification

Software companies continue to add and refine their built-in accessibility tools. People have multiple options for zooming and magnifying content. For more on how these features work, see:

• iOS v. Android: Mobile Accessibility Features 
• Microsoft Windows accessibility features
• Apple’s vision accessibility features.

Many people compensate for vision loss with glasses or contacts. But not all visual disabilities are fully correctable. Making certain sites are responsive to zooming and magnification is critical.

Browsers have built-in resizing options, so you must:

• Use text elements that allow the user to resize them
• Avoid using images as text for essential information.

Adjusting colors

Operating systems also continue to add ways for users to adjust their screen’s contrast. 

Some examples of ways users might change their screen’s color:

• Alter their contrast theme
• Apply color filters
• Permanently set their screen to night mode.

There are many contrast themes a user can select from, including switching to black and white or inverting colors. Color filters can help both people with low vision and people who have color-blindness. Someone who gets migraines triggered by light can benefit from setting their screen to night mode all the time because it reduces blue light. 

Websites should:

• Use well-contrasted color combinations (see WCAG guideline 1.4.3 Contrast (Minimum) Level AA) 
• Not rely on color alone for conveying meaning (see 1.4.1 Use of Color Level A) 

In summary

Tools allowing people with blindness or low vision to access digital information are constantly evolving and online content needs to do the same. The table below summarizes the tools discussed in this article, who uses them, and how to get started. 

Related reading: How to Meet WCAG (Quick Reference)