Blue-Yellow Color Blindness Tests
Neitz Color Vision Test requires no training--It can be administered and scored by virtually anyone, including human resource professionals, teachers, and safety supervisors. The Ishihara, on the other hand, must be administered and interpreted by a trained professional. The Neitz detects both red-green and blue-yellow color vision deficits, whereas the Ishihara identifies only red-green.
Blue-yellow color blindness: Those with tritanopia and tritanomaly have difficulty with discriminating blue and yellow hues.
Color blindness involving the inactivation of the short-wavelength sensitive cone system (whose absorption spectrum peaks in the bluish-violet) is called tritanopia or, loosely, blue-yellow color blindness. The tritanopes neutral point occurs near a yellowish 570 nm; green is perceived at shorter wavelengths and red at longer wavelengths. Mutation of the short-wavelength sensitive cones is called tritanomaly. Tritanopia is equally distributed among males and females. Jeremy H. Nathans (with the Howard Hughes Medical Institute) proved that the gene coding for the blue receptor lies on chromosome 7, which is shared equally by men and women. Therefore it is not sex-linked. This gene does not have any neighbor whose DNA sequence is similar. Blue color blindness is caused by a simple mutation in this gene.