A number of serious medical conditions present with a sign that can only be detected visually. Reiss et al,1 in their excellent article, point out that color blindness impairs recognition of blood in body fluids and thus can delay the recognition and diagnosis of an important diagnosis, such as a genitourinary or bronchogenic neoplasm. They state that physicians should be aware of this possibility in their color-blind patients and that regular laboratory testing of body fluids might be in order. Imagine then the plight of visually impaired individuals who not only may have difficulty with color vision, but also cannot perceive fine detail. Indeed, we have heard blind persons express their deep-seated fear of not being able to identify such a sign of morbidity, and they even cite examples of the serious consequences of late diagnosis among their visually impaired acquaintances.
Fielder AR, Griffith R. Vision Impairment and Health. Arch Intern Med. 2001;161(18):2266-2267. doi: