- Dichromacy characterized by a lowered sensitivity to green light resulting in an inability to distinguish green and purplish-red
- An inherited defect in perception of red and green; red-green colorblindness.
The term is derived from the name of Dalton, John(1766-1844) British chemist whose pioneer work on the properties of gases led to his formulation of the atomic theory. He also studied his own condition of colorblindness.
Dalton described his and his brother's affliction of colorblindness with defective perception of red and green in the first scientific paper he published. It was entitled "Extraordinary facts relating to the vision of colours, with observation" (Mem Literary Philos Soc Manchester 5: 28-45, 1798). It is the first recognized account of red-green colorblindness.