The Visual Effect of Colour Blindness
- Pages: 8
- Word count: 1839
- Category: Doctor
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The world is full of many different colours but not everyone gets to see them in the same way. “The first scientific paper about colour blindness was written by John Dalton in 1793 entitled Extraordinary facts relating to the vision of colours” (Fluck 5). Colour vision defects can occur at different stages in a person’s life. There are many different types, and each affects the person differently. People who get diagnosed with colour blindness, still can one day have the opportunity to see all the colours on the colour spectrum.
“Colour blindness is an abnormal condition characterized by the inability to clearly distinguish different colours of the spectrum. The difficulties can range from mild to severe. It is a misleading term because people with colour blindness are not blind. Rather, they tend to see colours in a limited range of hues; a rare few may not see colours at all” (Encyclopedia of Children’s Health). People refer to colour vision defects in many different ways, one is colour vision deficiency which is a group that represents conditions that affect the interpretation of colour. People who have a colour default can have difficulties telling apart some shades of red, green, and yellow. Any defect in the three cones will result in abnormal vision. The three cones let a person see red, blue, and green and let them see the special of colours. Red/green colour defects are the most common defect. A quite rare type of colour defects is blue/green colour blindness and it is more common for youth children to develop rather than adults. If an individual suffers from a disorder that person is more likely to develop blue colour defects. Some different signs can help people identify if they are suffering from a colour disorder (Colour Vision Deficiency),(Fluck).
If people have trouble telling if colours are blue and yellow or red and green that could be a sign that there could be a colour defect in their vision. Another sign can be that a person tells another person that there seeing the wrong colour, which can also be a sign that they have a colour vision defect. If someone can normally see the full range of colours and they start to notice a change in how they see colours they should visit a doctor. There are other ways to get diagnosed with a colour defect rather than just inheriting it (Bailey).
Colour vision defects are not always inherited, it is sometimes caused by different diseases like Parkinson’s disease and Kallman’s syndrome or even just from aging. A person can also lose their colour vision by disease involving the retina, eye disorders, or if areas of the brain are defected in the process of processing colour vision. Drugs can also have certain side effects on the way a person sees colour. Having a colour defect does not mean that the person is blind it just means the person can not see specific colours the same way people with normal colour vision see the colour. Taking a test to see if a person has a colour vision defect can help identify the type of defect they have (Bailey).
Different tests can help a person identify if they are having trouble seeing certain colours. The test that people most know of is the American Optical/Hardy, Rand, and Ritter Pseudoisochromatic Test. This test has a circular plate that is filled with many small coloured circles that are a variety of colours, people with normal vision can see the number of the coloured circles made up in the middle of the plate, but people who have a colour defect can not make up the number. There are different tests that can help a person identify what type of colour default they have. The test can help identify which one of the three genes got damaged (Encyclopedia of children’s health).
There are three genes that can cause different forms of colour defects, OPN1SW, OPN1MW, and OPN1LW. These three genes have key roles in a person’s colour vision and are found in the retina. There are two different types of light receptors cells, rods, and cones in the retina. These two light receptors cells send visual signs from the eye to the brain. Low light vision is provided in the rods and bright light vision is provided in the cones including colour vision. Each set of cones has a certain pigment that is affected differently to different wavelengths of light. The brain puts together all the three types of cones to create a normal colour vision. Each gene is affected differently and changes the way a person can see colour depending on what gene gets damaged (Colour Vision Deficiency).
The three genes OPN1LW, OPN1MW, and OPN1SW provide the information for creating the opsin pigments in cones. The OPN1LW gene is sensitive to the light in the yellow/orange part of the visual spectrum. The OPN1MW gene is sensitive to light in the yellow/green light and the OPN1SW is sensitive to light in the blue/violet light. There are three main forms of colour vision defects that are caused from the three genes getting damaged (Colour Vision Deficiency).
There are many different types of colour blindness but the most common types are red/green, blue/yellow, and blue cone monochromacy colour blindness. Most people who have colour defects are diagnosed with red/green colour blindness. This form of colour vision defect is more common in males than in females. Red/green colour defects are caused by defects in the OPN1MW gene. When the gene gets defected it leads to a lack of L or M cones that affects red-green colour vision. Defects on the OPN1SW gene cause blue/yellow vision defects. With these defects, it can cause everlasting destruction to S cones. Defects on S cones make it hard or sometimes impossible to tell the difference between shades of blue and green and dark blue and black. Blue cone monochromacy happens when genetics changes defect the OPN1LW and OPN1MW genes. When they get defeated they do not properly work correctly. If an individual has this condition only the S cones are working making it hard to see colour correctly. “Blue-yellow colour vision defects are inherited in an autosomal dominant pattern, which means one copy of the altered OPN1SW gene in each cell is sufficient to cause the condition. In many cases, an affected person inherits the condition from an affected parent” (Colour Vision Deficiency). There is a form of colour defect where a human can not see any colour (Colour Vision Deficiency).
Achromatopsia is when a human can not distinguish colour, it is caused by a disease in the retina. If a person inherits this it means both parents have a copy of the altered gene but they do not have the disease. Their children have a 25% chance of not getting the disease, a 50% chance of having an altered gene and a 25% risk of having both genes altered and the condition. Achromatopsia gene resides on chromosome two. People who suffer from a colour defect have different ways of telling colours apart (Encyclopedia of Children’s Health).
People that have red/green or blue colour defects use object shape or location to help distinguish colour. People with red/green colour defects can normally tell apart red or green if they can visually compare the colours. They normally have trouble telling apart colours if they do not have a reference. Males are affected more by colour defects rather than women (Encyclopedia of Children’s Health).
Males are normally affected by red/green and blue colour blindness. Females can be carriers but are not normally affected. One of the locations for colour vision defects is on the X-chromosome. If a female carrier has a son they have a 50% chance of being colour blind. If a female has red/green or blue colour blindness it shows there is an involvement of another gene. The inheritance pattern of colour blindness is normally carried in the males genes (Encyclopedia of Children’s Health).
X-linked recessive patterns are what is inherited in blue cone monochromacy and red-green colour vision defects. The X chromosome carries the OPN1LW and OPN1MW gene. Males carry these disorders more because they only have one X chromosome where females there’s two, so both have to be affected to cause the disorder. Fathers can not pass X-linked traits to their sons. To pass the disorder to an offspring all of the offspring X’s have to have colour-blind DNA. Males are more affected by red-green colour defects but both males and females are affected by blue-yellow defects. There have been demographics done on red/green colour blindness (Colour Vision Deficiency),(Conditions).
Researchers studying red/green colour blindness in the United Kingdom reported an average prevalence of only 4.7 percent in one group. Only 1 percent of Eskimo males are colour blind. Approximately 2.9 percent of boys from Saudi Arabia and 3.7 percent from India were found to have deficient colour vision. Red/green colour blindness may slightly increase an affected person’s chances of contracting leprosy. Preterm infants exhibit an increased prevalence of blue colour blindness. Achromatopsia has a prevalence of about one in 33,000 in the United States and affects males and females equally (Encyclopedia of Children’s Health). People who are coloured blind still might have a chance to see colour again.
There is no cure for colour blindness but there are ways people with this disorder learn to function with it. Most people can get used to their defects but for some, it’s harder. People who are coloured blind have to find jobs that do not deal with colours. Being diagnosed earlier will help prevent learning problems during an individual years at school, especially because some learning relies on colour perception. There are special lenses people use to enhance perception, there are filters available in either contact lens or eyeglass lens. The tinted lens in the glasses gives colour blind people the chance to see the bright lights that people with normal vision take for granted. These lenses do not work for everyone so if an individual is coloured blind a doctor can tell them if these lenses will work for them. People have been studying colour therapy on animals (Encyclopedia of Children),(Bailey).
Colour therapy has been tested on animals that are sensitive to blue and green wavelengths but not red light. After a few months of therapy animals could tell apart images made up of red dots but the untreated animals couldn’t make up the image. “Gene therapy is starting to work and is changing this field,” says Commander. “There’s a real need for new therapies for the people I see who are losing most or all of their vision due to inherited retinal diseases” (Dougherty). If the gene therapy catches on there might one day be a treatment for colour blindness(Dougherty).
There are many different ways in which a person can test to see if they are suffering from a colour vision defect. Every single individual is affected in their own way depending on the type of defect they suffer from. The world is full of many different colours in which we all view in our own unique way.