acquired color blindness
defective color vision that develops in a person with previously normal vision. Acquired forms of color blindness can be caused by retinal disease (e.g., glaucoma, retinitis pigmentosa), optic nerve disease (e.g., in multiple sclerosis), or injury to areas of the occipitotemporal cortex that are responsible for color processing, as in cerebral achromatopsia (see achromatism) and hemiachromatopsia. Systemic disorders (e.g., diabetes mellitus), anoxia, and many toxins (e.g., alcohol) can also produce color deficiencies. Acquired color blindness often differs from genetic forms of the condition (see color blindness). The discrimination of colors may be impaired in all parts of the spectrum, and the patient may have difficulty in identifying desaturated colors. Color blindness is typically present in the entire visual field, but that due to cerebral injury may be limited to the left or right half of the visual field.