Visual

Introduction

People with visual disabilities typically rely on changing the presentation of web content into forms that are more usable for their particular needs. For example by:

• Enlarging or reducing text size and images;
• Customizing settings for fonts, colors, and spacing;
• Listening to text-to-speech synthesis of the content;
• Listening to audio descriptions of video in multimedia;
• Reading text using refreshable Braille.

For these web browsing methods to work, developers need to ensure that the presentation of web content is independent of its underlying structure and that the structure is correctly coded so that it can be processed and presented in different ways by web browsers and assistive technologies. For example, some people do not see the content and rely on lists, headings, tables, and other page structures to be properly coded so that they can be identified by web browsers and assistive technologies.

Some people are only seeing small portions of the content at a time or are perceiving the colors and design differently. Some people are using customized fonts, colors, and spacing to make the content more readable, or they are navigating through the content using keyboard only because they cannot see the mouse pointer. An accessible design supports different presentations of the web content and different ways of interaction.

Examples of visual disabilities

• Color vision deficiency – includes difficulty distinguishing between colors such as between red and green, or between yellow and blue, and sometimes inability to perceive any color (often called “color blindness”).
• Low vision – (in some regions also called “partial sight”) includes poor acuity (vision that is not sharp), tunnel vision (seeing only the middle of the visual field), central field loss (seeing only the edges of the visual field), and clouded vision.
• Blindness – substantial, uncorrectable loss of vision in both eyes.
• Deaf-blindness – substantial, uncorrectable visual and hearing impairments.

Examples of barriers for people with visual disabilities

• Images, controls, and other structural elements that do not have equivalent text alternatives.
• Text, images, and page layouts that cannot be resized, or that lose information when resized.
• Missing visual and non-visual orientation cues, page structure, and other navigational aids.
• Video content that does not have text or audio alternatives, or an audio-description track.
• Inconsistent, unpredictable, and overly complicated navigation mechanisms and page functions.
• Text and images with insufficient contrast between foreground and background color combinations.
• Websites, web browsers, and authoring tools that do not support the use of custom color combinations.
• Websites, web browsers, and authoring tools that do not provide full keyboard support.

Stories related to visual disabilities

• Ilya, senior staff member who is blind
• Lee, online shopper with color vision deficiency
• Noor, teenager who is deaf and blind
• Yun, retiree with low vision, hand tremor, and mild short-term memory loss