Defect in vision that causes some colors to be perceived differently or not perceived as different tones, an example would be the inability to distinguish green and red tones. Depending on the type of defect, there are different types of color blindness, some more serious than others. It is a hereditary defect that affects only men, and the most common cause is an abnormality in the cells of the eye responsible for the perception and differentiation of color (the cones), it is also called color blindness.

Treatment: Currently there is no treatment for congenital color blindness, glasses or special colored contact lenses can be used, these helps distinguish between certain shades, but they do not return normal color vision.