Are You Color Blind?

The human eye

The human eye is one amazing instrument – a phenomenon of biological engineering, and the window through which we interact with our world.  The fastest and arguably strongest muscle – it is second only to the brain in its complexity. At Johnson & Johnson Vision Care, where I now work, our mission is to promote healthy vision for everyone.

This doesn’t mean just vision correction! It means treating the full range of optical conditions, from common myopia (short sightedness) to the more complex and currently incurable glaucoma –  and everything in between.  It means designing products that don’t just improve the quality of vision, but are also safe and non-damaging to this special organ.

It’s easy to just focus on simple vision correction, because 285 million people are estimated to be visually impaired worldwide, and only a fraction of them are treated. But in the spirit of Healthy Vision, I had a very interesting discussion with my coworkers about color blindness – and learned some pretty amazing things! Read on to take a hue test to see how accurately you see the lush colors of the world, and to hear about exciting research into curing color blindness.

How Do We Perceive Color?

The retina of your eye is covered by millions of light-sensitive cells, some shaped like rods and some like cones. These receptors process the light into nerve impulses and pass them along to the cortex of the brain via the optic nerve. Six million cones in each eye transmit the higher levels of light intensity that create the sensation of color and visual sharpness. There are three types of cone-shaped cells, each sensitive to the long, medium or short wavelengths of light. These cells, working in combination with connecting nerve cells, give the brain enough information to interpret and name colors.

How Common is Color Blindness?

About 8% of men and 1% of women have some form of color impairment. Most people with color deficiencies aren’t aware that the colors they perceive as identical appear different to other people. Most still perceive color, but certain colors are transmitted to the brain differently.

The most common impairment is red and green dichromatism which causes red and green to appear indistinguishable. Other impairments affect other color pairs. People with total color blindness are very rare.

 How Do I Know If I Am Colorblind?

The most common color blindness test is the Ishihara Test, which is a circle image composed of small dots of varying complimentary hues. Inside these circles are numbers drawn out in distinct colors – if you can see the number, you are not colorblind.  If you can’t make out the number, then you likely have some color blindness in that color range.

A more complex test is called the hue test, and it involves rearranging four sets of 25 tiles so that they are organized by hue from darkest to lightest.

Take The Test!

Click on the image below to take a hue test – afterwards it will plot your weak areas on a color graph so you can see where they are. They will also assign a numerical score for results called the total error score, this measurement is used to determine the severity of your color blindness. The results range from about 11 for normal vision, to 40 and above for severe color deficiencies. It’s a little longer than the Ishihara, but I prefer the numerical and graphical interpretation.


Munsell Color Test


Depending on your source, any score above 40 is considered color blindness, and zero represents a perfect score.  I personally scored 17, with a concentration of errors indicating that I am slightly red-green color blind. One of my coworkers scored 257, and we had a great follow up discussion on the color of traffic light signals and such.  For said coworker, green doesn’t mean go, white does.

Curing Color Blindness

In 2009, the idea of a cure for color blindness started to seem like an impending reality. A study co-authored by Jay Neitz at the University of Washington successfully used gene therapy to give two squirrel monkeys, who exhibited color blindness identical to humans, the ability to see colors they had never seen before. The monkeys, named Dalton and Sam, both lacked a gene known as L opsin that provides the information for L-Cones in the iris (long wavelength, red sensitive). This is the same cause for red-green color blindness in Humans. Using hue tests not too different from the one above, they saw a dramatic increase in color acuity.

No time frame for a main line drug for humans has been given, but we can no doubt expect rapid development on the technique – especially given its potentially far-reaching applications in curing other forms of more debilitating blindness in the eye. The prospects for application of this technique may well extend beyond color blindness as mentioned by Neitz,“…almost every unsolved vision defect out there has this component in one way or another, where the ability to translate light into a gene signal is involved.”

I believe in the not too distant future we could live in a world where disposable contacts deliver gene therapy to provide enhanced vision capabilities, from color to night vision.




Posted in Science, Shifting Perspectives, Technology. Tagged with , , , , , .

Leave a Reply

Your email address will not be published. Required fields are marked *