Photo: EnChroma®

Hyperallergic has a story about glasses being offered at Denver Museum of Contemporary Art which will enable the color-vision-deficient to see the art as they would if they didn’t have any color blindness. The glasses (4 pairs) have been donated by their manufacturer, EnChroma®, at whose website you’ll find a test to tell you how your color vision rates. They’ve also donated glasses to seven other museums.

The thought that color blindness might be corrected by clever lenses filtering the light appropriately is one of those ideas which is blindingly obvious once someone has thought of it, but which seemed unimaginable up till then. EnChroma don’t tell us exactly how they do it (why would they?) but their website provides quite a bit of information about color vision.

Color cone sensitivity. Picture: EnChroma®

We have two kinds of light receptors, rods and cones, located in the retina. Rods allow us to see in low light conditions: at night your color vision shuts down — that’s just not the rods’ job — while our three types of cones, blue, green, red, allow us to see bright light, and convert it into color vision. The cones of a person with normal color vision will be arranged so that their sensitivity ranges overlap slightly as shown above. In people with color blindness there is a greater overlap of the red and green curves so that in extreme cases it becomes impossible to distinguish between these two colors.

Color blindness is genetically inherited. It travels on the X chromosome and 1 in 12 men are said to suffer from the condition. Since a woman will have to inherit the gene from both parents, the likelihood of finding a color-blind woman is only about 1 in 200. (Both these rates strike me as surprisingly high, but I guess it’s not something that comes up in conversation that often.) Red-green color blindness is the most common variety, but there are several other conditions which can be broken down into three broad categories, Protan, Deutan and Tritan. Monochromacy and Achromatopsia are more extreme condition. Details about these conditions can be found at EnChroma’s website.

See also Color vision.