n. a person who is completely colour-blind. There are two types. The rod monochromat appears to have totally defective *cones: he or she has very poor visual acuity as well as the inability to discriminate colours. The cone monochromat has normal visual acuity: the cones appear to respond normally to light but to be completely unable to discriminate colours. It is possible in this case that the defect does not lie in the cones themselves but in the integration of the nerve impulses as they pass from the cones to the brain. Both types of colour blindness are probably inherited.
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