Colour Vision Defect By Daphne Wan

What is Colour Vision Defect? Colour Vision Defect is also know as been colour blind. It is a condition that affects a person's perception of colour. People who are affected by colour vision deficiency have a lot of trouble distinguishing between colours such as reds,yellows, blues and greens. There are three types of colour Vision defect: Red and green color blindness which is the most common in today's world, blue-yellow aka ( blue cone monochromacy) color blindness that is in the 7th Chromosome meaning it is not a sex linked trait therefore means that both males and females have equal chances of been diagnosed to it. Then lastly been being colour blind to all colours in general which is really rare.

Some people with Non inherited colour blindness also obtain this condition of colour vision deficiency due to their other health problems such as diabetes,liver diseases and any type of eye diseases. This is called

  • Symptoms and Signs that determine Colour Vision Deficiency-¬†Some significant symptoms and signs to know a person is colour blind is when a person struggles to differentiate colours that are displayed in front or at them such as words written on the board in different colour chalk for people at school. Another symptom is when a person says that they don't see any difference in the darkness and lightness of colours when there are obvious differences to particular colours such as reds,greens,blues and yellows that are constantly mixed with light and dark shades of the of their kind (eg light green and dark green). And lastly another sign and symptom to tell a person has colour defect is when a person is unable to see the brightness of certain colours in a normal way (when everything looks dark and neutral) eg. the light blue sky is not light in their eyes.
on the right is what normal vision people see and on the left is what red -green colour blindness people see. A person can find out that they are colour blind, if coincidentally them and another person view the image and talk about the image describing it as to what they are seeing. They shall soon find out that what they are both viewing are different due to one person being colour blind and the other not. Image credit- http://www.sparticl.org/topic/color-blindness/

How Frequent is it for People to be colour blind? Colour blindness is in approximately 1 in 12 men and 1 in 200 women throughout the world in which majority are from Northern Europe. 4.5% of Britain's population is colour blind by which all are mainly males.

Tests to see if a person is colour blind- Some tests to see if a person is colour blind is that if they are feeling that they can't differentiate between colours then they should go staight to an optometrist to get it professionally checked out. An optometrist will carry out forms of diagnostic tests that consist of patterned shapes and numbers in the form of coloured dots.

Another test that can be considered is using the ishihara colour blind test online where it provides sets of plates that have numbers in them, you have 3 seconds to view the image and then you must type in the number you see. At the end of the test according to the numbers you've gotten correct it will provide you an idea if you have colour Vision deficiency or not.

This is an example of what a Ishihara test looks like, can you determaine the numbers in the plates? . Image credit-http://www.somersault1824.com/tips-for-designing-scientific-figures-for-color-blind-readers/ishihara-test-color-blindness-disease-perception-test-2/

Where is Colour Vision defect more common in? Colour Vision defect is more common in people with a Northern European background or ancestry. Statistics show that 8 percent of men and 0.5 percent of women with the background have red-green colour blindness which is the most common type of colour blindness.

Are there treatments for colour blindness? Currently there are no cures for inherited colour blindness, however contact lenses or colour filters may be used to help a person's vision of light depending on the individuals preference, as not everyone thinks this treatment is effective for them. Although there are no current cures for inherited colour blindness in humans many scientists and doctors have been trialing a system of gene technology where injection of genetic material will be injected into the eye. (This treatment has not yet been tested on humans just yet).

source-http://www.colourblindawareness.org/colour-blindness/treatment/

How is colour vision defect inherited? colour vision defect is commonly inherited, meaning it is most certainly passed down by your parents. When a boy is colour blind (to the colours red and green) the blindness has been scientifically proven that the faultiness has been passed down by the mother. Which is due to her 23rd chromosome ( also known as the sex chromosome) that holds her dominant genes. Colour blindness is more common in males than females because women have two X chromosomes and men have one X and one Y chromosome, meaning that the chances for a male to be diagnosed with color blindness is easier than women as colour blindness can only be found in the X chromosomes. This been said men only need one faulty X chromosome to be colour blind whereas for women they need two faulty X chromosomes. Fathers who are coloured blind can only pass their faulty X chromosome to their daughters but only if the mother is a carrier who has passed that on to the daughter.

This is a pedigree chart of the inheritance of color blindness and where color blindness usually comes from in a family through generations.

Where is the Colour blindness gene known? Inherited red-green colour deficiency and blue cone monochromacy are all in a X-linked recessive pattern. The proteins and pigment genes that make up normal visions are called OPN1LW. They are the genes that resource instructions to making the proteins. OPN1LW Genes are found in the retina which is the sensitive tissue at the back of the eye ball. Furthermore the other gene located in the X chromosome is called OPN1MW which resources proteins for photopigments that allow people see lighter colors such as yellows and greens. Therefore for example if a person has more OPN1MW which is likely the case (as red- green colour blindnes is the most common of all) and only 1 copy of OPN1LW the person would have red-green colour blindness as they don't have even amounts of the genes to have normal vision as OPN1LW allows a person to only see lighter colours. Overall the gene in found in a person's X chromosome.

Is Colour Vision defect a chromosomal disorder or is it gene mutation? Colour vision defect is a gene mutation meaning the causes of colour blindness is due to it. As gene mutation makes a person lose completely, or have missing color cones in their eyes such as their red and green cones, make the person with the defect have difficulties in being able to differentiate the two colours. When there is an obvious and significant difference to those with normal vision.

This diagram shows a person with Monochromacy where only the rods are providing and the cones are not. In all types of Monochromacy or colour blindness it is when the eye is lacking either the cones or rods. http://www.theinkrag.com/colour_blindness/monochromacy.html

What is the life expectancy for people With colour Vision defect? The life expectancy for people with colour vision defect doesn't significantly differ to normal people, meaning they won't significantly have shorter lives due to their diesease. However colour blindness may lead to sudden incidents causing deaths examples include not being able to differentiate red stoplights and green go lights properly whilst driving a vehicle.

Where is Colour Vision defect more common in? Colour Vision defect is more common in people with a Northern European background or ancestry. Statistics show that 8 percent of men and 0.5 percent of women with the background have red-green colour blindness which is the most common type of colour blindness.

Prognosis for Colour Vision defect- When a Color blindness is inherited, the disease occurs and is present in both eyes and remains in the individuals for the rest of their lives.

Bibliography: Word document format: News article, website and book

Credits:

Eyeball image- https://scienceofparkinsons.com/2016/08/31/is-there-something-in-my-eye/ Pedigree chart- https://theworldwithoutcolour.wikispaces.com/Red-Green+Colour+Vision+Deficiency comparison picture of the balloon house- http://www.sparticl.org/assets/uploads/images/resource-images/61146-cropped.jpg

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