Colorblindness Essay, Research Paper
Colorblindness is a defect of vision affecting the ability to distinguish colors. There are many different types of colorblindness. Partial colorblindness is called dichromatism. The most common form is red-green and has a wide range of variability within this group from very mild to very extreme. The second most common form is blue-green, and a red-green deficit is usually associated with this form. The most severe form of colorblindness is achromatopsia (or monochromatism), the inability to see any color. People with achromatic vision see everything in shades of white, black, and gray, kind of like a black-and-white picture.
It is also known as daltonism, however colorblindness is the term more commonly used. Daltonism originated from John Dalton, a British chemist. John Dalton was the first person to write a detailed report, in 1794, on this condition. Dalton himself was afflicted with this disorder.
Colorblindness is a sex-linked recessive gene. Women need two genes to be colorblind. Men only need one gene on their X chromosome because there is no normal gene on the Y chromosome to counteract the colorblindness gene. This is a single gene disorder and is carried on the X chromosome. It is not environmentally influenced; it is a germ cell mutation (from the parent cells). Females can be carriers, but males cannot and are more commonly affected.
Approximately 8% (or 1 out of 10) men have some form of colorblindness and 0.5% (or 1 out of 200) women have some form of colorblindness. This disorder is present at birth, it does not occur later in life and is not triggered by any specific event. However, it may occur as a temporary condition following a serious illness. Colorblindness may exclude people from some jobs, such as being a pilot, where color vision is essential.
If a colorblind man and a woman with normal vision have children all of them will have normal vision. However, the defect is hidden in the daughters and they can pass it on to their daughters. If a colorblind man marries a woman whose father is colorblind, probably half of their children will be colorblind. If a mother has one colorblindness gene, there is a 50% chance that her daughters will be carriers and a 50% chance that her sons will be colorblind. If a mother has colorblindness, all of her daughters will be carriers and all of her sons will be colorblind.
Colorblindness is normally diagnosed through clinical testing. Several color vision tests are available through a physician or eye specialist (ophthalmologist). Testing for colorblindness is commonly performed along with other vision screenings. Several types of tests have been devised for the rapid diagnosis of colorblindness and of the particular variations of the condition. The Hardy-Rand-Rittler (H-R-R) and Ishihara tests indicate both the type and the degree of colorblindness. Another test, the Holmgren test, measures the ability to match colors.
Colorblindness is a life-long condition. There is no prevention for it because it is an inherited disorder. If you have this disorder, you must learn to cope with it. It can also have a positive side however. People with this can discern details and images that might escape normal sighted people. Most people compensate well for having this disorder.