2. Potential Barriers and User Requirements

Contents: Potential barriers, user requirements broken down by design element.

People with visual impairments may encounter a wide range of barriers as a result of their impairment:

• Content that is too small (text, images, etc.) and a lack of tactile information.
• Lack of alternative formats (e.g. separate digital files) or Braille versions for materials such as books, menus, navigation aids, etc.
• Lack of descriptions for information conveyed visually.
• Lack of alternative text for images, control elements (buttons, form fields, etc.) and other structural elements on websites and in other technologies.
• Lack of output options via a Braille keyboard for websites, documents and other technologies.
• Lack of visual and non-visual orientation cues, page structure and other navigation aids (e.g. lack of visible focus on hover, or lack of orientation sounds at traffic lights).
• Non-scalable text, images and page layouts on websites, or loss of information when zooming in.
• Lack of audio description or text or audio alternatives for video content.
• Insufficient contrast between foreground and background colours for text, controls and images.
• Inconsistent, unpredictable and overly complicated navigation mechanisms and page functions.
• Lack of support for user-defined colour combinations on websites, in web browsers and in authoring tools.
• Lack of keyboard support on websites, in web browsers and in authoring tools.
• Documents and forms that are not accessible (incorrect reading order, missing metadata such as document title and language, etc.) (Abou-Zahra, 2017).

There are many different types of visual impairments, which can occur in various combinations. It is also important to note that needs can vary depending on the context, e.g. time of day, location or even mood. It is therefore difficult to find a uniform design solution that meets all needs. Particularly in the field of digital accessibility, individual user customisations are of great importance for people with visual impairments.

The most important user needs for the digital environment have been summarised here, though these are not exhaustive. Further information is available in EN 301 549 and WCAG 2.2.

Brightness

Some people with visual impairments are extremely sensitive to light, a condition known as photophobia. Bright light from screens or other sources (the sun, lamps, etc.) can make seeing and reading difficult or impossible, and often causes headaches and eye pain in those affected. To counteract this problem, some people resort to various solutions, such as reducing the brightness of their screen or using an overlay. People with photophobia also prefer a dark-coloured background. It must therefore be possible for those affected to adjust the overall brightness of a screen (W3C, n.d.).

Contrast

Some people require lower contrast, whilst others require very high contrast. Those who require low brightness, particularly for backgrounds, generally need lower brightness levels and therefore also lower text brightness. Those affected choose background and text colours so that they provide sufficient contrast but are not too bright.

For many people with visual impairments, as well as older people whose contrast sensitivity decreases with age, a high contrast between text and background is essential for readability. WCAG 2.1 specifies in its guidelines a contrast ratio of at least 4.5:1 for normal text and images, with a few exceptions. For large text (i.e. 14-point and bold or larger, or 18-point or larger) and images containing large text, a contrast ratio of at least 3:1 is required. Colour contrast checking tools such as the Colour Contrast Analyser can be helpful for verifying the contrast ratio.

However, there are varying preferences regarding contrast. Some people use common colour combinations or colours from a limited colour palette, e.g. black text on a white background or vice versa, whilst others need to adjust background and text colours to suit their individual needs. Readable and optimal colour combinations therefore vary greatly from person to person and may even vary depending on fatigue and lighting conditions. It is therefore important that users are able to select the background and text colours from the entire colour spectrum (W3C, n.d.).

Use of Colours and Highlighting

When using many colours to convey information, for example in diagrams or graphs, many people – particularly those with colour blindness – may find it difficult to distinguish between colours and to read the information. Textures or patterns, such as dashed or solid lines or hatching, can help to distinguish between data points in diagrams, particularly when differences in value, hue and saturation are subtle and more difficult to discern.

In general, according to WCAG 2.1, important information should not be conveyed solely through colour. Particularly in the case of warnings, alerts and interactive page elements such as text links or buttons, a simple change in colour is not sufficient. Visual highlighting used to convey information requires a second visual cue, e.g. an icon, bold text, positioning, size, underlining, a frame, etc., or identifying text. The text conveying the same information may also be provided in context. Highlighting, e.g. using bold or italics, helps to distinguish important content from irrelevant content; however, this should not be used excessively. Although almost everyone understands that blue underlined text indicates a hyperlink, there are still websites that underline blue text without providing a link. This is particularly problematic for people with colour blindness, as they may rely on the underlining to indicate a link (Vorm, n.d.).

Text and Spacing

Some people with visual impairments need enlarged text to recognise the letters, whilst others – including, for example, those with tunnel vision – prefer smaller text so that they can see more words at once. Assistive technologies are available for text enlargement, such as screen magnification software or reading magnifiers. It is also possible to adjust the text size in the browser settings. However, not everyone is familiar with these technologies and customisation options; it is therefore advisable to allow users to manually change the text size or font size of the entire text without having to enlarge the entire interface (e.g. via a button).

The typeface also affects readability. In the digital realm, sans-serif typefaces – i.e. those without ‘feet’, such as Helvetica or Arial – are typically chosen. Entire blocks of text that are underlined or in italics, or text in capital letters, can make reading more difficult.

Spacing between lines, paragraphs, words and letters also affects readability; therefore, these should ideally be adjustable. Line spacing often helps with tracking. WCAG 2.1 defines the following in its guidelines:

• Line height (line spacing) should be at least 1.5 times the font size,
• spacing between paragraphs at least two times the font size,
• letter spacing (kerning) at least 0.12 times the font size,
• word spacing at least 0.16 times the font size.

Block-style text often disrupts the flow of reading, as there can be a great deal of space between words, making it difficult to follow the line of text (W3C, n.d.).

Link Descriptions

Descriptive and unambiguous link labels are important, particularly for screen reader users. They often use a keyboard shortcut to list all the links on a page, enabling them to navigate more efficiently. Therefore, link labels such as ‘click here’ lack context and should therefore be avoided (Vorm, n.d.).

Alternative Text for Non-Text Content

Visual information, such as graphics, images or text within images, is often inaccessible to people with visual impairments (uAG Technische Überwachung, 2022). Alternative text (or ‘alt text’) consists of short textual descriptions used to describe non-text content on websites, non-web documents and software for people with visual impairments. Non-text content includes images, graphics, videos and audio files. Screen readers can then read out the alternative text aloud. This text should be as short and concise as possible and reflect the content of the non-text element as accurately as possible.

Screen readers cannot analyse images and graphics to understand their meaning. For these reasons, alternative text must be provided to convey the content or function of images. For images, the alternative text should contain a precise description of the image’s content. If it is a photograph, for example, the alt text could describe the people in the picture, their clothing and the background. If the image is a graphic or a diagram, the alt text should describe the image’s content in a few words. It is important to note that whilst images used purely for decorative purposes do not require alternative text, they must be labelled as ‘decorative’.

Keyboard accessibility

People with visual impairments may use assistive technologies, such as screen readers. Users typically use the keyboard to navigate with a screen reader. Therefore, all interactive content, such as links, buttons, form fields or widgets, must be accessible and operable via the keyboard. The current focus should also be clearly indicated whilst navigating. Any functions that require a mouse or a touchpad/touchscreen should be avoided. For people with low vision, it can be very difficult to follow the mouse pointer across the screen (WebAIM, 2021).

Audio description

If content in videos is shown only visually and not explained further, this can cause difficulties for people with visual impairments. Audio description is an additional audio track that describes essential visual information and provides context for this information. In other words, a narrator describes what can be seen in a frame, such as key details about the plot, characters, or locations. On-screen text is also read aloud.