The user group I have identified that are in need of support and should be addressed in the design of a website are those with a visual impairment.
The degree of impairment that the design is targeted at are those persons whose eyesight is begining to fail, to those who are becoming partially blind.
The best general accessibility standards, that should be applied in the design of a website for visually impaired persons of the mentioned category, can be summarised as follows.
Limit or omit the use of graphical text.
The use of images of text (often used for important items such as headings or navigation) is undesirable for a number of reasons. Users who have low vision may prefer different fonts or colour combinations, may need to increase the text using browser options, or use magnification software to enlarge the text beyond the maximum size the browser can offer (an example of magnification software is the free Windows Magnifier found in Windows Accessibility Options).
Ensure that font size can be increased.
Ensure that text sizes are not fixed and can be resized in the browser. It is important that text is not a fixed size so that vision impaired users can increase the size of the text to make it more legible. Most Web browsers include functionality to let you increase or decrease the text in a Web page. You can put a link to information that will help the user adjust the display settings through the standard browser settings. For example a help link could be “How to Change Text Size” .
Use color carefully.
Use good contrasting colours. Do not rely on colour alone to convey information. Blind users may not be able to get information about colour definitions from their screen reading software and using colour also presents difficulties for colour blind users. Colour contrast can be measured and analysed. This analysis should be compared against colour combinations and contrast against the W3C colour recommendations.
Provide skip links.
Provide a means of skipping over often numerous navigation links with a ‘Skip to content’ link and ‘Back to top’ link between sections of long pages.
Ensure that all navigational functionallity is available through the key board as well as the mouse.
This can be checked by tabbing through links and forms using the keyboard to ensure they can be accessed – and in a sensible order. This is important because users with vision impairments will not have good hand-eye co-ordination and are more likely to interact with the website solely through the use of their keyboard.
Provide alternative text.
Ensure that all images have meaningful alt text. This alt text is read out by the screen reader so that the user understands what is being shown on the screen. Providing alternatives to text that can be changed into other forms such as large print, or maybe a more simplified form of the language.
Screen enlargers are available for people with visual impairment. They work like a magnifying glass. They enlarge a portion of the screen as the user moves the focus—increasing legibility for some users. Some screen enlargers allow a user to zoom in and out on a particular area of the screen.
Screen readers are also available and are software programs that show graphics and text as speech. A screen reader is used to talk everything on the screen including names and descriptions of control buttons, menus, text, and punctuation.
Further reading – including the latest updated information on Visual Impairment afflictions and website design accessibility check out the following sites: