Making Pages Accessible for People with Visual Field Scotomas

September 28, 2021

According to the National Institutes of Health, about 6 percent of Americans aged 12 or older have visual impairments — that’s 14 million Americans, and more than 11 million of those people have uncorrected impairments. 

Digital content needs to be accessible for these individuals, but visual impairments can affect user behavior in different ways. Designing your website for blind users can be extremely helpful, but web accessibility isn’t just for the blind; if a disability doesn’t affect the user’s entire field of vision, they may access your website with a standard web browser using a keyboard and mouse. 

A scotoma is a partial loss of vision that affects an otherwise normal visual field. Also known as “blind spots,” scotomas vary in severity and location. Minor scotomas may not have much of an effect on a person’s daily routines, but some scotomas can make certain activities difficult — including web browsing. 

To make your content accessible, you’ll need to consider the full spectrum of disabilities during design and development. Fortunately, the Web Content Accessibility Guidelines (WCAG) provides excellent guidance.

For people with scotomas, web browsing can be frustrating

Vision disabilities can have a profound impact on how people perceive web content. For example:

  • Some types of scotomas can cause blurred vision. If a website has a poor color contrast ratio (the text isn’t significantly brighter or darker than the background), text may be unreadable.
  • Many people with scotomas use screen magnifiers or change their browser settings to increase the size of text. Some websites don’t function as intended when magnified. 
  • A scotoma may hide some navigation elements from the user’s view. 
  • Pop-ups and other elements may disorient the reader, particularly if they’re using a screen magnifier to focus on certain content.

It’s important to remember that scotomas can change vision in a variety of ways. Accessible design needs to consider the full scope of vision disabilities.

Some users may prefer to browse with assistive technologies like screen readers, which convert text to braille or audio. Others magnify their screens to read content, and others change their monitor settings or attach glare-reduction filters to make scotomas less noticeable when reading.

Certain types of scotomas are temporary — people who experience migraines often have temporary scotomas, and the spots can occur due to stress or hormonal changes. This is an important consideration when discussing web accessibility: While some people with scotomas may use screen readers or make other adaptations to navigate the web comfortably, others may not change their browsing habits in any significant way.

Web design decisions can improve the user experience for people with scotomas

The WCAG framework is the most frequently cited set of international standards for web accessibility. Because the framework uses a principle-based approach, it’s an extremely useful tool for design and development. By following the success criteria, content creators can ensure that their content is reasonably accessible for people with scotomas — regardless of their exact browsing behaviors.

To develop a better understanding of how design choices affect people with scotomas, here are a few tips to keep in mind. 

Make sure users can zoom in or re-scale your content.

WCAG success criterion 1.4.4, “Resize Text,” requires websites to be scalable to 200% without losing functionality or content.

You can determine whether your website meets this requirement by zooming to 200% with your browser. Does the page adapt to new dimensions? Are you still able to navigate comfortably, and is the content still understandable?

Read: Give Yourself an Accessibility Test: Zoom Your Page to 200%

Keep related elements close together. 

Pages should operate in a predictable way. If a website tells users to “click below to fill out our form,” the next element should be a link to the form — not another paragraph of text.

Make sure labels and controls are in close proximity to content, and review your website’s structure to ensure that it operates as expected in different browsing conditions (such as when a screen is magnified or when using a keyboard alone for navigation). Review WCAG success criterion 2.4.3, “Focus Order,” for more guidance.

Take steps to improve the reading flow for text content.

A user with scotomas may prefer to scroll with a horizontal or vertical scrollbar to read text. These users often enlarge text to make it more legible. If the text doesn’t “reflow" — the text doesn’t automatically shift to fit the page — the user may need to scroll back and forth several times to read information. 

Review the World Wide Web Consortium (W3C) recommendations to ensure that your text is optimized for one-direction and single-column scrolling. 

Follow WCAG recommendations for color contrast ratios.

WCAG success criterion 1.4.3, “Contrast (Minimum)” requires a visual presentation of text (and images of text) to have a color contrast ratio of at least 4.5:1, with limited exceptions for large text, incidental text, and logotypes. The Bureau of Internet Accessibility offers the Color Contrast Accessibility Validator, a free tool for testing pages for contrast issues.

Consider all of your users when designing for accessibility

Remember, the goal of accessible web design is to accommodate all types of users. In order to optimize your content for all users, you’ll need to review WCAG recommendations. Test your website regularly and provide visitors with a way to submit feedback about accessibility concerns. 

Accessibility has numerous benefits, and by considering all users — and the various ways that disabilities affect their browsing habits — you can reach a much wider audience. To determine whether your site conforms with WCAG standards, get started with a free and confidential website scan

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