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Visualisation Tool Help

I know all this, take me to the Visualisation tool...


This tool allows people to see websites the way people with various visual impairments do. Currently it covers varying degrees of colour blindness, diabetic retinopathy, cataracts, macular degeneration and glaucoma.

This tool was developed to make people aware of the issues around website accessibility and the difficulties faced by people with visual impairments.

More information on how to use the tool can be found below.


Due to the limitations of current browser technology the visualisation tool page does not comply with the Web Accessibility Guidelines (WAI) and can only be viewed on Windows Internet Explorer version 5.5 and above.


It is very easy to use this tool. The first step is to decide what page you want to view and fill in the URL in the text field. You can also use the photo provided already.

Colour Blindness

Click on one of the colour blindness buttons (30%, 70% or 100%) to view different degrees of colour blindness. This tool copies an image of the page being viewed which is then filtered and overlaid onto the page itself.

If the underlying page changes for any reason for example due to dynamic elements or being scrolled down then the 30% and 70% views will have a ghosting effect.

Note how it becomes difficult to distinguish between orange and green when suffering from this impairment. A website which uses, for example, orange text on a green background could be very difficult to read for somebody with this type of colour blindness.

Diabetic Retinopathy

The diabetic retinopathy view can be toggled by clicking on this button.

Diabetic retinopathy is a progressive disease. It starts out with just a few spots which slowly grow bigger and eventually join up and covers most of the view. This makes it difficult to view fine details such as small fonts.


The cataracts view can be toggled with this button. Note that it affects the whole page rather than just the viewing area.

Cataracts make it difficult for a person to focus on fine details such as small fonts. It may also distort the image (not shown) in specific areas.

Macular degeneration

The macular degeneration view can be toggled with this option. When it is active you can click on the overlay and move your mouse around to simulate how somebody may move their eye across the screen.

Macular degeneration starts from the point where the nerves enter the eye and spread out from there. It makes it difficult for a person to see things straight on and they have to resort to looking at things through the sides of their eyes.


The glaucoma view can be toggled with this option. When it is active you can click on the overlay and move your mouse around to simulate how somebody may move their eye across the screen.

Glaucoma, more commonly known as tunnel vision, restricts a person's vision to a very small field. People with this impairment have to scan across a page to be able to view the different parts.


Some people suffer from combinations of these impairments, although it is less common. You can activate more than one impairment to simulate this. If you want to combine colour blindness with any of the others then it must be the last to be applied. Combining the cataracts with either macular degeneration or with glaucoma does not work unfortunately.


The functionality on this page is derived from the Accessibility Toolbar. This utility provides the above functionality and more by installing a new toolbar on your Internet Explorer browser. The Accessibility Toolbar can be downloaded from The Colour Blindness simulator is based on the Colour Blindness Checker from Q42.

Go to the Visualisation tool.