Color is in the eye of the beholder… and their retinal cones…

Color blindness, despite it’s serious sounding name, is usually not considered a serious ailment. However, many people neglect to realize what a hindrance this condition could be; imagine never being able to see the color purple, or pick the green skittles out of the bag, it’s tragic really. Even less people realize the science behind this phenomenon, specifically the fact that there multiple different types of color blindness. This blog post was inspired by a video I recently found in my Facebook page of a young man who suffered of colored blindness finally being able to see the world with the help of the corrective glasses ‘EnChroma’ (http://laughingsquid.com/a-colorblind-man-is-overwhelmed-when-he-sees-purple-for-the-first-time-wearing-special-glasses/).

Let’s get down to the details of color blindness, and then we’ll discuss how these glasses manage this amazing technological and medical feat. The most common form of color blindness is caused by damage or malformation of certain cones in the retina. If you’ve ever taken genetics you know that color blindness is the go to example for x-linked genetic conditions, this is why men have a higher incidence of color blindness, because they only have one x chromosome and if it supplies crappy eye genes the individual is SOL… whereas females have two sets of x chromosomes, so one may be bad, but the other could be normal and construct a normal eye no problem.

What the cones in your eyes look like. Left is a normal eye which has three colored cones, and right is a malformed eye which only absorbs green and blue light.

What the cones in your eyes look like. Left is a normal eye which has three colored cones, and right is a malformed eye which only absorbs green and blue light.

People with normal vision have three types of light cones in their eyes that function properly: red cones, green cones, and blue cones (there are actually 7 million cones in every eye!). Each of these cones are sensitive to their respective color and allows your eye to sense combinations of light waves, this is how you are able to see colors like purple which excite your blue and red cones which then combine together and voila… purple! The three main types of genetically inherited color blindness are those that have defective blue cones (tritanope blindness, a problem with the S-cones), defective green cones (deurteranope color blindness, a problem with the M-cones), and defective red cones (protanope blindness, a problem with the L cones).  Tritanope is actually the rarest type and deurteranopes and protanopes are about equally common. These cones are defective in the way that they are absorbing colors their not supposed to, thus L cones are absorbing green, rather than red, making it difficult for the optical nerve to observe green (and any colors that incorporate green).

What people with different types of color blindness are able to see.

What people with different types of color blindness are able to see.

So how do the glasses in this video work? How are you able to, non-surgically, correct damaged or absent color cones? These glasses only work with the more common type of color blindness and it does so by filtering light through the glasses to ensure the light spectrum that reaches the users cones are at a specific region between red and green. This specific region causes a distinction between the red and green cone signals which causes improved separation and allows the cones to absorb their assigned colors which allows the user to better see red and green hues.

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Pretty cool, right?

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