<P> Some subtle forms of colorblindness may be associated with chronic solvent - induced encephalopathy (CSE), caused by longtime exposure to solvent vapors . </P> <P> Red--green color blindness can be caused by ethambutol, a drug used in the treatment of tuberculosis . </P> <P> Based on clinical appearance, color blindness may be described as total or partial . Total color blindness is much less common than partial color blindness . There are two major types of color blindness: those who have difficulty distinguishing between red and green, and who have difficulty distinguishing between blue and yellow . </P> <P> Immunofluorescent imaging is a way to determine red--green color coding . Conventional color coding is difficult for individuals with red--green color blindness (protanopia or deuteranopia) to discriminate . Replacing red with magenta or green with turquoise improves visibility for such individuals . </P>

What are the two types of color blindness