Did you know that upwards of 8% of men are colorblind? No, we are not talking about the tie they chose to wear with that shirt, though perhaps for some men, that is a very legitimate excuse. Women are affected far less with only 1 out of every 200 affected by colorblindness. The light sensitive tissue lining the inner surface of our eyes is called the retina. The retina is made up of rods and cones. The rods give us our night vision but do not distinguish color. The cones perceive color.
The cones, each contain a light sensitive pigment which is sensitive over a range of wavelengths (each visible color is a different wavelength from approximately 400 to 700 nm). Genes contain the coding instructions for these pigments, and if the coding instructions are wrong, then the wrong pigments will be produced, and the cones will be sensitive to different wavelengths of light (resulting in a color deficiency). The colors that we see are completely dependent on the sensitivity ranges of those pigments.
People with normal cones and light sensitive pigment are able to see all the different colors and subtle mixtures of them by using cones sensitive to one of three wavelength of light – red, green, and blue. A mild color deficiency is present when one or more of the three cones light sensitive pigments are not quite right and their peak sensitivity is shifted. A more severe color deficiency is present when one or more of the cones light sensitive pigments is really wrong.
There is not one type of colorblindness. Each of us have different color sensitivities. Take a look at these Ishihara color tests to see what numbers you see in each plate. The answers are at the bottom of the page. If you have trouble reading any of these, please call us and schedule an eye exam and let our doctors work out a solution for you.