What is Colour Blindness ?

Colour Blindness Simplified

Colour blindness is a form of blindness where a person cannot distinguish between some or specific colors

People with color blindness aren’t aware of differences among colors that are obvious to the rest of us


Types of Color Blindness

Red-Green Color Blindness

Color blindness are due to the loss or limited function of red cone (known as protan) or green cone (deutran) photopigments


  • In males with protanomaly, the red cone photopigment is abnormal
  • Red, orange, and yellow appear greener and colors are not as bright
  • This condition is mild and doesn’t usually interfere with daily living


  • In males with protanopia, there are no working red cone cells
  • Red appears as black
  • Certain shades of orange, yellow, and green all appear as yellow


  • In males with deuteranomaly, the green cone photopigment is abnormal
  • Yellow and green appear redder and it is difficult to tell violet from blue
  • This condition is mild and doesn’t interfere with daily living
  • Deuteranomaly is the most common form of color blindness


  • In males with deuteranopia, there are no working green cone cells
  • They tend to see reds as brownish-yellow and greens as beige


Blue-Yellow Color Blindness

Blue-cone (tritan) photopigments are either missing or have limited function



  • People with tritanomaly have functionally limited blue cone cells
  • Blue appears greener and it can be difficult to tell yellow and red from pink
  • Tritanomaly is extremely rare


  • People with tritanopia, also known as blue-yellow color blindness, lack blue cone cells
  • Blue appears green and yellow appears violet or light grey
  • Tritanopia is an extremely rare autosomal recessive disorder

Complete Color blindness

People with complete color blindness (monochromacy) don’t experience color at all


There are two types of monochromacy:

Cone monochromacy:

  • This rare form of color blindness results from a failure of two of the three cone cell photopigments to work
  • There is red cone monochromacy, green cone monochromacy, and blue cone monochromacy
  • People with cone monochromacy have trouble distinguishing colors because the brain needs to compare the signals from different types of cones in order to see color in display

Rod monochromacy or achromatopsia:

  • This type of monochromacy is rare and is the most severe form of color blindness
  • It is present at birth
  • None of the cone cells have functional photopigments
  • Lacking all cone vision, people with rod monochromacy see the world in black, white, and gray