Ivan Allen College of Liberal Arts Accessibility Online Course

Medical Disabilities: Vision Impairment

What is Vision Impairment?

There are many different conditions that can affect a person's vision, including but not limited to:

The list above is presented roughly in order from easiest to hardest to correct.  That is, anyone in bright sunlight can usually move to a darker area, though there could be situations when it's not ideal to move right away.  Astigmatisms and presbyopia can be corrected for with glasses, contact lenses, or sometimes with laser surgery.  The other conditions are not as easily treated, if treatable at all, and macular degeneration could worsen in time to the point of complete vision loss. 

Most of these impairments are "invisible", meaning that one cannot look at a person and tell if she or he has one of these impairments.  Therefore, it is important to recognize that far more people than you think could suffer from some form of vision impairment, even the higher level impairments.  Some, such as Presbyopia, happen to a large number of people as they get older.

How Does Someone with Vision Impairment Experience the Web?

Bright Light

Reading content in bright light is similar to having color blindness, in that it becomes harder to tell colors apart, especially colors that are similar in hue or contrast.

Presbyopia

Small print and fine visual details are very hard to read, especially if the user does not have their glasses handy (people without other vision problems may keep reading glasses on hand that they use only for reading).

Color Blindness

For single color blindness (most commonly blindness to red, but could be green or blue), everything that has a basis in that primary color will lack that color, causing colors to appear more similar than for someone with normal color vision.  Two-color blindness increases the level of similarity between colors.  Full color blindness (rare but does occur) causes everything to appear in shades of grey.

Macular Degeneration

As the macula is at the center of the retina, degeneration of it results in a loss of vision at the center of the visual field, much like a hole.  As the disease progresses, this "hole" in the visual field can get larger.  As there is usually better vision in the macula than around the macula, degeneration results in the loss of the area where tasks like reading will normally occur.

Web Accessibility for Vision Impairment

There are several best practices for making website content as accessible as possible for people with vision impairment:

  • Avoid really small print, which is hard to process.
    • With the college Drupal web toolkit, never use the 80% or 90% font sizes on body text – they should only be used on headings, and even then only when absolutely necessary.
  • Provide more spacing so that text is broken up and not in big clumps:
    • Break up long paragraphs into multiple short paragraphs (and long sentences into multiple short sentences).
    • When creating lists provide space between list entries.
      • With the college Drupal web toolkit, you can add space after every line by selecting the text of an ordered or unordered list and apply the "Normal" format.  This format is found on the first / left-most formats drop down on the editor formatting bar.
  • Make links and buttons large, so they can easily be spotted (but don't make them too large or overly wordy)
    • Avoid single words as links, especially short meaningless words like "here" or even "click here".  An ideal link will be in the neighborhood of two to five words that clearly describe the destination of the link.
    • Never suppress the marking of links with some form of an underline and alternate color from the body text color.
  • Avoid unnecessary formatting, as this can actually interfere with comprehension:
    • Use italics, bold, etc. minimally, only where real emphasis is needed (and never use underling, which is disabled in our Drupal web toolkit, as it is reserved exclusively for links).
    • Never use all capitals: text in all capitals is much harder for someone with vision impairment to read, as there is no longer any distinctive shape to each word and these people rely on recognizing word shapes when recognizing individual letters has become too difficult.  However, when words are printed in all capitals, most will look like prefectly rectangular blocks. Compare and contrast these two examples:
      • Ivan Allen College of Liberal Arts
      • IVAN ALLEN COLLEGE OF LIBERAL ARTS
    • Avoid centering text: centering a short title is okay, but avoid centering full sentences and never center an entire paragraph.  Even people without vision problems can have trouble reading a centered paragraph since every line is starting at a different horizontal position.
  • Support text-to-speech and screen magnification tools, which are often used by people with stronger impairment or full vision loss to help them perceive website content.
    • Avoid using infographic images to convey workflows and other complex relationships:
      • Whenever possible, use standard HTML lists and tables to put information in plain text that text-to-speech readers can process.  That said, be sure you are using tables correctly, providing proper headings and only using them for connecting data to heading values (tables should not be used for plain lists).
      • If an infographic is still desired, also provide the same information again in plain text (using HTML lists and tables as applicable) so that those who cannot see or properly process the infographic have a second option.
    • Avoid using images to custom format a heading or other piece of text.  If you can't format a heading the way you want with the tools in our web toolkits, then you likely should not be using the formatting you had in mind.