How does one become colorblind?
It’s a matter of biology. Here’s a basic explanation of how a male usually becomes colorblind.
A helpful biological fact is that women have 2 Y chromosomes and men have 1 X chromosome and 1 Y chromosome. As you might expect there is a bit of “chance” involved. Just like when a woman becomes pregnant, there is a 50/50 chance of the baby being a male and a 50/50 chance of the baby being female.
Each parent contributes a chromosome–since a woman only has Y chromosomes she contributes one Y chromosome. If she’s a carrier, there is a 50/50 chance of the mother contributing the defective (such a harsh word) chromosome to the baby. The father rolls the dice and if he contributes a Y chromosome, the baby will be a girl with 2 Y chromosomes. However, if he contribute an X chromosome, the baby will be a boy.
Will the boy be colorblind? It all depends on whether the mother contributed the colorblind chromosome-and the chance of that is 50%. Likewise, the chances of a girl being a carrier are also 50%. It boils down to whether the mother contributed the defective chromosome or not. If she did, the boy will be colorblind and the girl will be a carrier.
So in a nutshell, if the mother is a carrier AND she’s going to have a boy, the chances of the baby being a colorblindguy are 50%. It all depends on whether or not the mother contributed the defective chromosome.
The American Academy of Ophthalmology published a report on ethnicity and colorblindness.
The study found:
- 5.6 percent of Caucasian boys
- 3.1 percent of Asian boys
- 2.6 percent for Hispanic boys
- 1.4 percent of African-American boys
The study also pointed out that usually children at 4 years old could be screened for colorblindness. The study reported:
“Many times children with color blindness will perform poorly on tests or assignments that employ color coded materials, leading color blind children to be inappropriately classified by ability at school…”
Rohit Varma, M.D., chairman of the Department of Ophthalmology at the University of Southern California
ophthalmologist is a medical doctor (MD) or a doctor of osteopathic medicine (DO) who specializes in eye and vision care.
How about a colorblind female child?
The parents of a colorblind woman would require that the mother be a carrier (or colorblindness) AND the father be colorblindguy.
Read this story about a woman who is colorblind and she owns a pair of the Enchroma glasses.
How does she cope?: “Now, my rule for work clothes is I only wear stuff that goes with black.”
What’s going on inside of the Eye?
“Normal human color vision is trichromatic thanks to a cluster of three types of photoreceptors known as cones, which are present in the retina. These cones are sensitive to short wavelengths (S), medium wavelengths (M) and long wavelengths (L). However in Europe, about 8 percent of men and 0.5 percent of women in the Caucasian population suffer from some type of congenital anomaly in the performance of some of the cones, which causes color vision deficiencies. This anomaly is a sex-linked recessive trait, with the red-green color vision deficiency being the most frequent in humans.”