Color blindness
Although the name is blue-yellow color blindness (tritanopia), people affected by this type of color blindness can usually tell the difference between blue and yellow. Instead they cannot tell the difference between blue and green, and also yellow and violet.  It is different from the other types of color blindness because it is not linked to sex.  It is equally possible for males or females to develop blue-yellow color blindness. It is caused by having few or no cones in the retina which can sense short wavelength light.