The principle is that those with a severe deficiency of colour vision will not see the symbols with colours lying on their confusion loci, even those constructed using the most saturated colours, but will see the symbols that have colours lying on the other confusion loci.I have read and accept the Wiley Online Library Terms and Conditions of Use Shareable Link Use the link below to share a full-text version of this article with your friends and colleagues.Learn more. Copy URL.
Richmond Products produced a new edition in 2002 that has been reengineered to rectify shortcomings of the original test. Aoc-Hrr 2Nd Edition Test Trial Of TheThis study is a validation trial of the new test using a larger sample and different criteria of evaluation from those of the previously reported validation study. Colour vision was diagnosed using the Ishihara test, the Farnsworth D15 test, the Medmont C100 test and the Type 1 Nagel anomaloscope. Sensitivity and specificity become 0.98 and 1.0, respectively, when the fail criterion is three or more errors. Those with redgreen colour vision deficiency were correctly classified as protan or deutan on 86 per cent of occasions, with 11 per cent unclassified and three per cent incorrectly classified. All those graded as having a mild defect by the Richmond HRR test passed the Farnsworth D15 test and had an anomaloscope range of 30 or less. ![]() Its classification of protans and deutans is useful but the Medmont C100 test is better. Those graded as mild by the Richmond HRR test can be regarded as having a mild colour vision defect but a medium or strong grading needs to be interpreted in conjunction with other tests such as the Farnsworth D15 and the anomaloscope. The Richmond HRR test could be the test of choice for clinicians who wish to use a single test for colour vision. It has been much loved by the cognoscenti of colour vision because it included plates to detect tritan colour vision deficiency, as well as the protan and deutan deficiencies and had a carefully designed set of plates to differentiate protan, deutan and tritan deficiencies and grade their severity. The HRR provided the clinician with more information than the Ishihara in a test that was just as easy to administer. The Ishihara test, renowned for its high sensitivity and excellent specificity for the detection of protan and deutan deficiencies, has no tritan plates and the number of errors made gives little indication of severity. Moreover, its four protandeutan classification plates are not very reliable. On the basis of his colorimetric analysis, Dain 7 concluded that it was a pale imitation of the real thing. Richmond Products published a further edition in 2002, the colours of which have been carefully reengineered with the assistance of Jay and Maureen Neitz and James Bailey. It comprises 24 plates each displaying either one or two symbols, which can be a cross, a circle or a triangle ( Figure 1 ). The symbols are constructed of coloured dots on a background of grey dots. The coloured dots have chromaticity coordinates that lie on or close to the protan, deutan or tritan dichromatic confusion loci that pass through the chromaticity coordinates of the grey background colours. The patient is asked to name the shape of each symbol they see and indicate its location, which can be in one of four quadrants of each plate. The colours of the symbols lie (in this case) on the protan and deutan confusion loci. One of these plates has no symbol so that patients understand that a symbol might not be seen on some plates. These are followed by 14 plates designed to grade the severity of the deficiency and to differentiate protans, deutans (10 plates) and tritans (four plates). The colours of the symbols lie on the protan, deutan or tritan achromatic confusion loci and become increasingly saturated as the patient proceeds through the plates.
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