Achromatopsia is complete color-blindness in humans. These are people who are unable to see colors and only see the world in black, white, and shades of gray. This condition can be congenital or acquired, but typically is a result of a congenital condition where the eye and brain are incapable of perceiving color or achieving satisfactory visual acuity at high light levels, such as normal daylight.
This condition is caused by a recessive gene that is carried on the X chromosome and affects men more often than it does women. This syndrome also exists in partial form (trouble seeing specific colors such as in red-green color blindness) and is referred to dyschromatomia.