Unable to distinguish the color red. See wordnikxref
The Century Dictionary (Public Domain)
Use "red-blind" in a sentence
"To red-blind eyes, it must indeed be horrible, watching that enormous darkness grow until it had gulped all the stars and only instruments revealed anything of the absolute night outside."
"Three or four per cent. of the population are color blind -- "red-blind""
"The red-blind will select green and brown; the green-blind picks out reds or lighter brown."