Reviews
Reviews of Colour Blindness: Causes and Effects will be posted to the web site when they are published.

Lighting Research and Technology
The following review is reproduced from Lighting Research and Technology, published by the Chartered Institution of Building Services Engineers.

"To see the world in monochrome, where objects are differentiated solely in terms of lightness and texture is, fortunately, very rare at less than 1 in 10 million of the population. The condition is known as 'achromatopsia' (i.e., without colour vision) and is the only true form of colour blindness. However, most people calling themselves 'colour blind' do actually see colours, albeit they perceive the world distinctly differently from the majority of people, so it would be more appropriate to say that they have a colour vision deficiency. While we know from careful colour matching experiments that the majority of people show only slight variations in their colour matches, there are three small groups of people (totalling about 5% of the population, mostly men) who show systematically marked deviations in colour matching performance. These are people who have either a deficiency of red, green or blue sensations and, of these three, the red and green colour vision deficiencies are the more common with a recessive sex-linked pattern of inheritance. A major part of this book is a clear description of the retinal characteristics leading to colour vision deficiencies, their patterns of inheritance and the tests used for their detection. The practical consequences of defective colour vision are well discussed and the cautionary remarks about the unfounded claims of therapeutic corrections using tinted lenses are essential reading for all who vainly hope for a 'cure'. As such, it is a useful resource to teachers, parents and those who possess this interesting vision anomaly.

The first two chapters are disappointing; in both there is an ambiguity in the use of colour terms for describing both the physical property of light as well as the perception. Light, as a physical property, has no colour and neither do physical objects have colour. Physical descriptions of different light sources and different objects can only be made in terms of their different emitting or reflecting wavelength characteristics within the range of the visual spectrum. Following coding by the retina and visual cortex of these light wavelength characteristics in the incident light, the perception of colour is a construct of the brain. So also are there neural correlates of colour constancy in the brain and it is inadequate to describe this important phenomenon merely in terms of experience.

The author, Donald McIntyre, a physicist with a colour vision deficiency, has made a noble attempt to describe, for those with normal colour vision, how the world of colour appears to people who have a specific inherited colour vision deficiency. In this respect the book includes some fascinating comparative illustrations between normal and defective colour vision, including different appearances of the Websafe palette, the colour codes of the London Underground map and various fruit on a market stall. But, of course, it is impossible to demonstrate to those with an inherited colour vision deficiency what the world looks like to someone who has normal colour vision. This is because it is impossible for anyone to conceptualise a sensation they have never experienced. In reality, we do not know exactly how the colour defective person perceives the world, only that they make systematic colour confusions. However, it is principally for these practical illustrations and related discussion that the book will be a useful resource for lighting designers, architects and interior designers."

Review by Professor Adrian R. Hill, School of the Built Environment, Heriot-Watt University, Edinburgh
Lighting Research and Technology 35 (3) 281-282, 2003
© The Chartered Institution of Building Services Engineers

Support for Learning
The following review is reproduced from Support for Learning, a journal of the National Association for Special Educational Needs.

"Donald Mcintyre is a colour-blind physicist who has written an accessible scientific work which summarises the causes and effects of a condition affecting about one in 12 men and one in 200 women - although nearly one in six women carries the gene that is responsible for the condition. Based on his personal experience he introduces us to a 'forgotten handicap' which is a life-long condition.

An aim of the book is to improve communication between those with colour vision deficiency and those with normal vision. We learn that colour vision deficiency is the preferred term for all types of colour deficiency. Colour blind, whilst strictly inaccurate, is the common English term used for linguistic convenience.

The first part of the book describes the several types of colour vision deficiency and how they are passed from generation to generation. The physics of light, colour and vision are outlined, as is diagnostic assessment. The second part introduces the reader to the difficulties experienced in everyday life and uses computer-generated illustrations to recreate the world as seen by people who are colour-blind. Awareness of colour blindness only comes as a consequence of interaction with colour normals or with some aspect of the man-made environment. Following the examples given it seems surprising how a high proportion of colour-deficient people reach adulthood without realising their condition. At the end of each chapter is a clear and concise summary designed to consolidate understanding.

Part Two provides practical advice for parents and teachers. Through understanding the world of the colour blind we can better understand the limitations experienced in everyday activities. A short section of Chapter 6 goes through the early visual development of children and their colour learning experiences at school and at home. Although no statistical relationship is found between colour-deficient vision and school achievement it is possible to understand the effects that it may have on school behaviour. Some tips to help identify colour-blind children and some practical advice are offered.

There is an interesting and useful chapter (seven) on careers, which links in with earlier references to art, food, sport, gardening and other daily activities. The book ends with a comprehensive overview of the techniques for overcoming or dealing with colour blindness which are available, with a consideration of their effectiveness. The necessary theory in the book is brought alive through the computer-generated illustrations. To someone without a colour vision deficiency they say it all. I would recommend this book as a reference work of interest to the colour blind, their families and their teachers."

Review by Lindsey Rousseau,South East Region SEN partnership manager
Support for Learning Volume 18, Number 3, page 143, 2003
© NASEN. Any use of this article, other than for personal research, requires the permission of the National Association for Special Educational Needs or from Blackwell Publishing.
www.nasen.org.uk

Journal of Biological Education
The following review is reproduced with permission from the Journal of Biological Education, a journal of the Institute of Biology.

"The sex-linked inheritance of red-green colour blindness is such a fixture in school biology texts that many will be unaware that there are several types of colour vision deficiencies (CVDs) with a variety of causes. The first half of this text deals with the nature of colour vision and describes the range of deficiencies, their transmission and diagnosis. The latter part of the book aims to answer the question 'What does a colour-blind person see?' It then describes how these deficiencies can affect everyday life for those concerned.

The author of the book (we are told) is a colour-blind physicist, so the text is an interesting amalgam of physics and biology. The historical treatment of colour and colour-vision deficiencies is very well done and the author includes some excellent anecdotes en passant. For example, the book explains that the colour of aircraft rescue dinghies was changed from yellow to orange because of the paucity of blue cones in the fovea of the normal retina (about 3% of all cones). My only biological disappointment was that the text didn't deal with the molecular genetics of red-green colour-blindness in sufficient detail.

Above all, the author has managed to cut through the complicated technical terms that confuse the unwary in this field. If you are not sure of the difference between a protanopic dichromat (someone who is red-blind) and a deuteranomalous trichromat (someone whose green sensitivity is abnormal) then this book will enlighten you and help you understand what it means for those concerned.

The 16 colour pages included are used to show those of us with normal colour vision what the world looks like to those with CVDs. In fact most of those with CVDs still see the world in colour, but very much dulled down. If you want to see what a map of the London Underground or a fruit stall looks like to one who is red-blind, then this book is for you.

With 8% of all males in UK affected then there is good reason for all those concerned with the design of websites to take account of how their creations will be seen (or not) by those whose colour vision is defective. There is a fascinating chapter on the effects of CVD on everyday life and in such fields as art, sport (problems in recognising the brown ball in snooker) and medicine.

Overall, the author should be commended for raising the profile of a condition which affects so many. More than any book before it, this book will help those who do not have colour-vision deficiency understand what it is like for those who do."

Review by George Fussey, Eton College, Windsor
Journal of Biological Education 37 (2) page 102, 2003.
© Institute of Biology
www.iob.org

Clinical and Experimental Optometry
The following review is reproduced with permission from Clinical and Experimental Optometry, the journal of the Optometrists Association Australia.

"This is a splendid little book that every optometrist should buy and read and which optometry students should also study. It is a little book of 164 pages in A5 format beautifully printed on good quality paper and less than a centimetre thick. It is a steal at 9.95 pounds sterling or about $30.

It is a compact book but it is crammed with information including snippets of fascinating information about colour and defective colour vision that will be new even to those who are well informed about colour. Did you know that William Gladstone the Prime Minister of Great Britain from 1868 to 1874 was also a classical scholar and that he analysed Greek literature for the usage of colour terms? He concluded they had defective colour vision because they used so few colour terms. The book also discusses other ethnic differences in colour vocabulary. One Danish anthropologist researching on a Polynesian island was told that "we don’t talk much about colour here" when he showed Munsell colours to the inhabitants. Did you know magenta was named after the blood spilled at the battle of Magenta in 1859? Did you know that there is a Websafe colour palette of 216 colours widely adopted by web site designers and that they have recognised the special needs of colour deficient users? There is a colour plate on page 122 of the Websafe palette, which is also represented as the deuteranope sees it. On the opposite page is a chart of 27 Websafe colours with a representation of how they are seen by each of the three kinds of dichromats. You can also see how a fruiterer’s display of fruit looks to each kind of dichromat. If you are interested in this but too mean to buy this book you can see some good simulations of the colour blind world at Jay and Maureen Neitz’ web site at www.neitzvision.com.

Now what is really fascinating about this book is that the author has dichromasy. He knew this from childhood and was denied entry into several possible careers including flying. He became a physicist and in the laboratory always makes sure that someone else checks that he had wired up coloured electrical cables correctly. He researched the book to provide a bridge between colour vision defectives and colour normals. His research has been excellent. I found no serious error and I learned a lot. We should not be surprised that he done his homework well - after all, LC Martin, WD Wright and FHG Pitt were physicists and they did all the basic quantitative research on defective colour vision. I am intrigued by a dichromat writing so authoritatively about colour and colour perception. It’s a bit like talking about God. You are told he exists but you have never seen Him. This is what gives this book its special quality and one of the reasons you should buy it. It is colour vision from another viewpoint. You well could buy some copies for resale to your colour defective patients. The book was written in part for those whose have defective colour vision but they would need to be pretty bright because the book, although very clearly written, covers a lot of technical ground. It is not an academic book but there are a few well-chosen references for each chapter at the back of the book.
The book is divided into two sections: the first is about colour and defective colour vision and the second is about the effects of defective colour vision. The first section covers light and colour, colour vision, the colour vision deficiencies, including a good account of modern genetics, and diagnosis. The second section covers the appearance of colours, the every day life experiences of the colour blind, the impact of colour deficiency on choice of career and a hard-nosed critique of the various devices said to help people who are colour blind. The chapter on everyday life experiences is especially good.

It is interesting to note that most of us who are interested in this subject are politically correct and refer to colour vision deficiency, not colour blindness or defective colour vision, which are thought might cause offence to those afflicted with colour deficiency. McIntyre is not worried about these semantics and talks about colour blindness despite being colour blind himself.

The book is privately published so you may need to buy it direct from the author whose address is given as 33 Eaton Road Chester CH4 7EW UK but maybe the OAA bookshop will buy some copies for sale. You can also order it on the web either through www.daltonism.org.uk or www.amazon.co.uk ."

Review by Professor Barry L Cole
Department of Optometry and Vision Sciences, University of Melbourne, Australia
Clinical and Experimental Optometry May 2003, 86 (3), page 194
© Optometrists Association Australia

Junior
The following review is reproduced with permission from the September issue of Junior, "The World's Finest Parenting Magazine".

"Imagine what life would be like if bananas were blue, grass was yellow and every shirt in your wardrobe looked the same.
Colour blindness affects about one in every twelve boys and can be extremely debilitating from a very early age (think of how many baby books and toys involve the recognition of colour). This book is an in depth exploration of the causes and consequences of colour blindness and how it affects individuals in everyday life.
The level of detail is astounding and because it is written in a pretty factual style, it is sometimes difficult to read and comprehend. Saying that, if your child is colour blind it is an invaluable resource to have on your bookshelf."

Junior, Issue 38, September 2002, page 104
© Beach Magazines and Publishing, 2002
www.juniormagazine.co.uk

Optometry Today
The following review is reproduced with permission from the October 4 issue of Optometry Today, the Journal of the Association of Optometrists

"This is a popular paper-back account of colour blindness, which is of great value and likely to fascinate all those who share the author's inherited difficulties with colour perception. It is well illustrated and pleasantly written.
McIntyre, a physicist, has delved widely to cover light sources, colour names, colour mixing and elementary aspects of ocular structure. The introduction offers a summary of relevant genetics, frequently standing back from subtleties. Many sixth formers and first year students will benefit from this approach, as will all needing insight into "what the Daltonic subject is likely to see" and those everyday practical effects of Daltonism which abound in art, transport, occupations and leisure pursuits.
An excellent range of coloured plates shows practical situations such as coping with the London Underground map. The text skips through many colour vision tests, several likely only to be found second-hand, but would-be users must beware of some inaccuracies. Delightful anecdotes, historical asides and examples of colour language abound. Chapters end with summaries, while a range of repetitions tends to surface and there is little attempt at comprehensive acknowledgement or referencing."

Reviewed by Professor Robert Fletcher
Optometry Today, Volume 42:19, Issue 4 October 2002, Page 26
© The Association of Optometrists 2002
Optometry Today

Optometry and Vision Science
The following review is reproduced with permission from the August issue of Optometry and Vision Science, the Journal of the American Academy of Optometry

"This book aims to provide a bridge between colour defectives and colour normals. It sets out to describe what the colour-blind see, to explore the consequences of defective colour vision and to give practical advice on dealing with some of the difficulties that may occur." (p. 4) In the eight chapters of Colour Blindness: Causes and Effects, plain-spoken physicist Donald McIntyre realizes this aim in the same way that I did in 15 years of teaching color vision deficiencies to optometry students. McIntyre starts with a discussion of light in the Newtonian tradition. He takes us through trichromatic, opponent-color, and Retinex color vision theories, although he does not use the Retinex word. McIntyre proceeds on to the genetics of human color vision and instruments used to evaluate human color vision deficiencies. Next, he turns to phenomenal appearances of two-dimensional color displays, using recently written computer algorithms. He then turns to something of true originality. He describes his own social difficulties that he has experienced as a consequence of his protanopia, the complete absence of the red cone rhodopsin from his retinas. He dwells on career requirements for color vision and laments his own career in military aviation, lost through detection of his protanopia at an enlistment attempt (p. 4). Finally, he catalogs various devices used in an attempt to improve color vision in the deficient. He finds no successful device.

This is a genuinely useful and attractive book. It has 37 figures, 19 in color. This book is not targeted to eye care professionals, but rather to counseling professionals and families for which color vision deficiency is present. McIntyre's use of the undefined phrase, "statistically significant" (p. 100), makes me think that he is writing to the reader with at least a university degree in the natural or social sciences. Although McIntyre's grasp of the color vision literature is solid, he does not attempt to provide scholarly citations. McIntyre has supplied illustration credits for 13 of the 37 figures. I defended a doctoral thesis in color vision in 1976 and have followed the psychophysical and biochemical technology and literature closely during their rapid development between 1976 and 2002. I can recognize the literature sources for the remaining figures by recollection from memory and, where memory fails, by comparison with books from my private library. This is also true of the text. McIntyre has rendered his own illustrations where credits are not given, but their sources are easy to identify.

This is the first book to cite an important review article by Neitz and Neitz, who suggest a blood test for specification of color vision deficiencies revealed by failure of Ishihara plate readings. Deoxyribo-nucleic acid (DNA) is extracted from blood cells, and polymerase chain reaction primers for DNA sequences specific for different cone rhodopsin genes, both typical and atypical, are used to amplify the sequences. The amplified sequences are hybridized with labeled DNA probes. This hybridization technique, called Southern blotting, defines the specific cone rhodopsin genes present in a given subject. The spectral sensitivities associated with many typical and atypical cone rhodopsins have been determined by spectrophotometry of these photopigments extracted from animal cell cultures. Psychophysical testing of color vision has always been troubled by lack of spectral resolution. This blood test s likely to supersede psychophysical testing. McIntyre correctly points out that this is likely to be important in the differential diagnosis of acquired and congenital color vision deficiencies (p. 54).

Figure 31 has four alternative color images. The first image represents the appearance of the London Underground railway map to a color-normal individual. In the second image, the hues have been transformed in a computer hue-weighting process to appear as they would to a protanope(red cone rhodopsin absent). In the third image) the hues have been transformed to appear as they would to a deuteranope(green cone rhodopsin absent). In the fourth image, the hues have been transformed to appear as they would to a tritanope (blue cone rhodopsin absent). The transformed images show how color-coding in graphics can confuse color-deficient individuals. The three transformed images clearly differ from the untransformed image. However, the protanopic representation and the deuteranopic representation appear to be very similar. Figures 32 and33, using different base images, have the same problem. Vienot and colleagues have performed a similar transformation of an image, but their transformations are all clearly different from each other. I suspect that McIntyre’s images look fine on a computer monitor but lose quality when printed. Identical hue rendering from monitor to print is an unsolved problem for the computer industry.

Color rendering is also a problem for the subtle hue variations of the 1931 CIE chromaticity diagram (Fig. 14) and the Farnsworth-Munsell 100-hue test (Fig.24). Color-normal individuals appreciate the changes in the 100-hue test when viewed in the clinic, but the photographic reproduction of Fig. 24 has made the ordered hues look identical from one extreme to the other in one box that contains25% of the hues of the color circle.

I detected two single-character typographical errors and two syntactical errors. I detected two British usages ("draftpieces" on p. 59 and "Millennium Products" on p. 152) that escape the experience of North American readers. I detected one error of fact: I am unaware of an American Society of Ophthalmology (p. 142).

McIntyre has not previously published a medical article or book. He does not pretend to be more than an interested layman despite his doctoral degree in physics. "The book is based entirely on the work of others . . ." (p. 160). Nevertheless, he demonstrates an obsessive interest in color vision deficiency. He describes his courting of many vision professionals in his acknowledgements (p. 160). McIntyre presents a thorough and conservative discussion. He runs seriously wrong only in two places. One place is in a discussion of the Meares-Irlen Syndrome (p. 61), where he does not appear aware of the great controversy surrounding this syndrome. A simple review of the 37 titles accessed on March 31,2002 from PubMed, the computerized index of the peer-reviewed medical literature maintained by the U.S. National Library of Medicine, reveals the extent of this controversy. The second place is his deviation from centuries of genealogical practice in descendancy tree charts in his discussion of inheritance (Figs. 20 and 21). It is customary to represent each successive generation at an ordered distance from the propositus.

The book appears to be self-published; the Dalton Press Web site (www.daltonism.org.uk) has no other books or information listed. The price is absurdly low for a book that is this attractive and informative. As a publishing proposition, it would be interesting to know in 2 years' time how many copies have been sold at the offered price. Of course, advertising effort must be factored in.

Another interesting factor to consider is why this book has no competition. Books on life-threatening diseases written by physicians targeting patients are widely available, but there is none on color vision deficiency. Why has no dean of optometry or chairman of ophthalmology encouraged their eminently qualified faculty members to write such a book?

This forthright book ends abruptly without an epilogue, but there is a fascinating, silent epilogue written in urtext, as the psychoanalysts say. In the middle of the book, McIntyre suggests his inability to recognize emotion in others because, as a protanope, he cannot detect a blush, reddish by definition. ". . . the colour-deficient person may appear to be insensitive in their [sic] ability to detect blushing, pallor, or ill health. . . . These things matter, whether in marriage or other important relationship such as parent and child." (p.109) This is original and important to the psychologist.

McIntyre laments the loss of his childhood dream to be a military aviator; a life in the physics laboratory could not offer compensations for dreams of glory (p. 4).His physiological deficiency deprived him forever. As a child, he had no sense of any deficiency. I, too, had childhood dreams of glory as an aviator. Despite wearing a correction for myopia, I came to the eye clinic of the Philadelphia Naval Hospital, and the examiners permanently turned me away from the gates of the U.S. Naval Academy, despite a Senatorial letter of appointment in hand. John McCain, a U.S. Senator today, graduated from the U.S. Naval Academy and proceeded to a naval aviation career. My pedigree includes a 600-year line of English admirals; ships never fail to turn my head. I wince when I see the massive plinths in Anglo-American cities memorializing my naval forebears and the cozy pubs bearing their names and filled with ship models. Does the naked statue of Isaac Newton placed in 1999 into the courtyard of the British Library on London's Euston Road compensate? The statue was based on a tongue-in-cheek drawing by Newton's critic, William Blake. Physiological deficiencies defeat dreams."

REFERENCES
Neitz M, Neitz J. Molecular genetics of color vision and color vision defects. Arch Ophthalmol 2000; 118: 691-700.
Vienot F, Brettel H, Ott L, Ben M'Barek A, Mollon JD. What do colour-blind people see? Nature 1995; 376:127-8.

Michael C. Barris
BOOK REVIEW Colour Blindness: Causes and Effects
Optometry and Vision Science
Volume 79, Issue 8, Pages 476-477
© The American Academy of Optometry 2002