I'm cross posting this review of an article about color vision defects in 
histopathology to the Histonet and PATHO-L lists.

Russ Allison at the Coleg Meddygaeth Prifysgol Cymru (University of Wales 
College of Medicine) very kindly sent me a photocopy of "Deficient colour 
vision and interpretation of histopathology slides: a cross sectional study." 
 Poole CJM, Hill DJ, Christie JL, Birch J.  British Medical Journal 
1997;315:1279-1281.

J.L. Christie, the pathologist involved in this study, is at Russells Hall 
Hospital, Dudley, U.K.

270 male pathologists and technologists, 28 of whom had color vision 
deficiencies, were asked to evaluate projected Kodachrome slides that might 
create problems for someone with red-green color blindness.

No surprise that the most errors were made light microscopic identification 
of Myco. tuberculosis, presumably with red bacilli seen on a blue background. 
They also had trouble seeing pagetoid melanoma cells stained with colloidal 
iron on a PAS background, Congo red stains with amyloid showing green 
birefringence, and several other stains some of which I don't understand from 
a very fragmentary description. Some errors were made in interpreting immune 
stains, but the description of the stains is unclear. No fluorescent stains 
were presented.

An optometrist evaluated color vision using Ishihara plates and other 
conventional tests. Deficits were graded as mild, moderate, and severe, with 
more errors being made by men with worse color vision deficits. It was 
observed that individuals with severe color vision deficits were 
underrepresented in the study group.

The authors reviewed the rather sparse literature on the topic. They conclude 
that "the colour vision of all histopathologists and [histotechnologists 
should be] assessed. If they are found to have a severe protan or deutan 
deficiency, they should be counselled and advised to adopt a safe system of 
working....Ideally histopathologists should have their colour vision tested 
before entering the specialty."

I find this article less than convincing, and its conclusions disturbing. The 
strong implication that the pathology careers of people with color vision 
deficits should be restricted is unwarranted by the evidence presented.

Certainly red-blue contrasts in special stains need to be avoided. Light 
microscopic acid-fast stains are obsolete, and clinically dangerous because 
of their insensitivity.

(I have normal color vision myself.)

Bob Richmond
Samurai Pathologist
RSRICHMOND@aol.com