Visual

Introduction

People with visual disabilities typically rely on changing the presentation of digital technology 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 browsing methods to work, developers should use style sheets to separate content from its presentation and correctly code the structure so that it can be processed and presented in different ways by 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 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 digital 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:
  • Vision that is not sharp or clear (low visual acuity)
  • Intolerance to light (photophobia or light sensitivity)
  • Inability to distinguish bright and dim areas of images or text against a background (contrast sensitivity)
  • Inability to obtain information when looking straight ahead (field of vision loss; can be central, peripheral, or scattered)
• 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
• Lexie, online shopper with color vision deficiency
• Marta, marketing assistant who is deaf and blind
• Elias, retiree with low vision, hand tremor, and mild short-term memory loss