Have you ever been accused of being colour blind? I have been told I was colour blind by Sheila a couple of times a week for years. Not knowing for sure I decided to try some colour blindness tests on the internet.
Before the test I did a little research. The way I understand it, men are more likely to be color blind than women, and mother’s typically pass it along to their sons but not their daughters. People who are color blind (in my experience) don’t like to admit it to anyone!
My cousin was a classic case. He knew he was colour blind but was in denial. One time he had a Chevy van and one night it was stolen. He reported it to the police, describing it as a brown van. A few days later the police “found a van that matched that description, but it was green.” It was then and only then that my cousin admitted that his van might be green. Sure enough it was his van. It was trashed unfortunately. Luckily, the next van he bought was white.
Most people who have trouble seeing various spectrums of light have what is called inherited color blindness. The genes for vision which are passed down from their parents have an error in it. This is why color blindness tends to run in families.
The non-profit ‘Colour Blind Awareness’ has compiled statistics on colour blindness. About 8% of men and 0.5% of women worldwide have some sort of color vision deficiency.
There are seven official diagnoses of color blindness: four different types fall in the red-green category, two are in the blue-yellow spectrum and one type of vision completely lacks in color.
Our eyeballs have two kinds of photoreceptors in the retina that are designed to absorb light. Named after their shapes, they are called rods and cones.
Rods are overly sensitive. They are the reason your eyes will adjust in a dark room, allowing you to see basic shapes. The human eye has eighteen times more rods than cones. But the cones are what give us fine detail and color. They work best in bright daylight. All types of color blindness have to do with diminished (or absent) functionality in the cones.
The human eye contains three different types of cones. S-cones (short-wavelength absorbing cones) help us see blue, M-cones (medium-wavelength absorbing cones) reveal green, and L-cones (long-wavelength cones) interpret red light. The absence of any of the three types of cones is what accounts for different types of color blindness.
About a month ago, Sheila and I were in kitchen looking out on the backyard. I said, “I never realized how much Muffin’s colour matches the grass!” Muffin was our orange cat. Sheila said, “It’s time to try that “Colour Blindness Test’ on the internet.
Red-green color blindness result in the individual seeing a world described as murky green with hints of blue and yellow. Browns, oranges and reds are easily confused, and pale shades difficult to distinguish.
Blue-yellow color blindness is less common. This color blindness make it difficult to tell the difference between blue and green, as well as yellow and red.
Although color blindness stems from a cone not functioning in the retina to some degree, people adapt to live normal lives. People who can’t see colour at all are only one in every 33,000 people. For these individuals, the world exists in black and white, much like old-time television.
Color blindness is not always inherited. It can be caused by environmental factors and can affect each eye individually to different degrees. Some ways color blindness can be acquired are aging, brain trauma and chronic illness.
This test consists of circles filled with dots, with a number in the center of a circle. If you can see the number, chances are you are not color blind. The tests consist of a series of different circles, each with a number.
I tried half a dozen tests first. On each test I couldn’t identity one to three of the numbers. Sheila’s tests were perfect. She said to me, “I knew you were colour blind.” Now I don’t have an appetite to argue that I’m not!
