Color Blind St. Patty's Day: I hope this is green!

If you can read the number "45" in the image on the right, you belong to the approximately 93% of the world that is not color blind.  For the rare 7% of us, that image is nothing but a circle of scattered, colored dots.  I know, it's hard to believe that some of us cannot see a number that is clearly sitting smack in the middle of that circle.  Welcome to the world of color blindness.

When those with color blindness tell their friends about their unique dilemma, the first two questions are: 1) "So you can't see any colors?" and 2) "What color is that over there?"  Color blindness is somewhat of a misnomer because true color blindness, the inability to see anything but black and white, is almost non-existent.  Instead, most people are red-green color blind.  This usually means that when the colors red and green are held together closely or presented in certain shades, an individual may be unable to differentiate between them.  I know that sounds ridiculous to those with normal color vision, but the problem is actually biologic.  Those with color blindness have defects in photopigments in their retina and are therefore unable to perceive certain colors correctly.  Furthermore, it is actually a genetic issue since the genes for these photopigments are on the X chromosome.  Without getting into the the mechanism of gene transmission, just know that this makes color blindness predominantly a male condition.  It is inherited from mothers that function as carriers but don't actually have the condition.

You might be wondering how people with color blindness can actually function normally.  After all, how do they know when to stop at a stop light?  Rest assured, there is a reason we pass our driver's tests and don't run into intersections on a daily basis.  The reason is that a stop light "red" actually does look red and the "green" does look green.  These shades are generally very easy to differentiate as are those of roses, plants, strawberries, blood, spinach, and apples.  The trouble arises with man-made objects: clothes, Google Maps traffic (come on Google, help us out!), confetti, school mascots, and TV.  So on this day, St. Patrick's day, don't discriminate against the guy at the bar and his brown t-shirt.  He just didn't have the luck of the Irish.