Color, much like sound, is measured and received in wave lengths. Each color variation of the rainbow is transmitted and accepted by your body through these waves. The human eyes are amazing creations in and of themselves, with the ability to differentiate these waves and interpret them to create the image you see. Compare the human eye to a camera. First, you have your lens on the outside, it has the ability to focus on images and project the image to the back of your eye where your retina is. The retina had special nerve cells, called cones and rods, that contain pigment cells which react to light. Rods only have a single type of pigment. Your rods cells have the same reaction to all waves of light. Rod cells help with night vision. Cones, however, are the mastermind behind your color vision. There is an array of pigments in these types of cells. Some of these cells interpret short wavelength light, others interpret medium wavelengths and yet others react to the much higher wavelengths. If all your cones cells have all of their photopigments and they are working properly, then you are able to see all the colors on the spectrum. However, if you are missing or having issues with any of these photopigments, they you will have a color deficiency, otherwise known as color blindness. There are varying levels of color blindness according to which pigments are missing. If you have no pigments at all in your cones, then you will not be able to see any color at all. This is a condition known as achromatopsia. Mild and even intermediate cases of Color Blindness can be treated with corrective lenses. Go to Color Blind Corrective Glasses to see an array of choices to help with your colorblindness.