There is a great deal of information to be found on the web and this selection of links does not aim to be comprehensive. They have been chosen where they supplement or update material in Colour Blindness: Causes and Effects.

Achromatopsia
This form of colour vision deficiency is given only a short treatment in the book. The Achromatopsia Network web site gives wide ranging information and support.

Design for the colour deficient
The explosion of the world wide web has stimulated work on the legibility of colour displays by the colour deficient. There are several sites giving good advice on colour design and showing simulations of colour deficient vision. Some offer software to transform colour images.
The Colors for the ColorBlind site gives background information on colour deficiency, some sample Ishihara charts and a set of colour charts to assist in web design.
A comprehensive set of material and software for handling web colours is provided by Visibone.
Vischeck is an innovative site. As well as offering several version of simulation software, it introduces a novel process termed Daltonizing. This adjusts the colour values of an image to reduce colour confusions for dichromats as far as possible, and so can be used to improve legibility of diagrams.
The School of Business at Rutgers University is investigating the relevance of colour vision deficiency to the marketing of consumer products. Professor Carol Kaufman-Scarborough has published a survey on her web site. This is designed to investigate the responses of both colour normals and colour defectives, with the aim of producing public policy guidelines. The survey is designed to be completed on-line.

Groups
Several research groups maintain their own web sites. As well as up to date research infomation, many display simulations of colour deficient vision and some sample vision tests.
The Neitz Laboratory in Wisconsin is a centre for colour vision research, specialising in genetics.
The Colour Group of Great Britain is a multidisciplinary group for those interested in all aspects of colour vision.
The Applied Vision Research Centre AVRC at the City University in London maintains an active research programme in colour vision, as well as providing testing services mentioned below.
The International Colour Vision Society (ICVS) operates at international level.

Lenses and Filters
The Chromagen lens is manufactured by Cantor and Nissel in the UK.
A wide range of colour filters is available in the UK from Lee Filters.

Products
The following companies offer a selection of testing materials and books:
A range of colour vision testing materials may be obtained from Keeler.
Also in the USA, Richmond Products Inc offers a complete range of colour vision testing devices and screeners, including the new 4th edition of the HRR plates.
Arlene Evans has published a book aimed at 9-12 year olds and their parents, entitled Seeing Color: It's My Rainbow Too. An Introduction to Color Vision Deficiency (colorblindness). Details on www.CVDbooks.com

Testing
A full diagnosis of colour vision deficiency requires a specialist testing centre. Two major centres are the University of Manchester Vision Centre in Manchester and the City University in London.
Several colour vision tests are to be found on the Web. They cannot be relied on as a substitute for a test arranged by a professional. The testing conditions are uncontrolled and the accuracy of colour reproduction depends on the quality of the monitor and set up. Having said that, many are remarkably effective.
A new web based colour vision test from the Applied Vision Research Centre at the City University requires the viewer to detect the direction of movement of a coloured image.