What Are the Main Types and Causes of Color Blindness?
The inability of the human eyes in which they won’t be able to perceive red, yellow, blue or green colours, is called the colour blindness. Colour blindness is not any form of blindness but it is the inability or deficiency of the way a person sees colours. Normally, any person who is colour blindness will have trouble seeing one or two colours and they will perceive them in a different way in comparison with the person with normal colour vision. For example, if a person has blue-yellow colour blindness, then they may see these colors red and green.
When any person watches an object, it’s image is being projected on the screen which is called retina and is located at the back of the eyes. Retina is a neural membrane line which is made up of two types of photoreceptor cells which are known as rods and cones. These are responsible for perceiving objects which are in the dark or at night and won't be able to perceive color. Approximately, there are 120 million rods present in each retina. Cones are responsible for perceiving the colors in the presence of light.
Types of Color Blindness
The type of color blindness can be determined by the functioning of the cones. The types of color blindness are as follows –
Monochromatism:
Any person who is having monochromatism will not be able to distinguish between any color, which is usually because of the absence or total malfunction of the cones present on the retina. A person will be able to distinguish the color objects according to their brightness. This type of blindness is very rare and it occurs usually in the combination with other problems related to vision.
Dichromatism:
Any person who is having dichromatism usually has two functional types of cones and the third type of cones will be missing or not functioning properly. This results in not perceiving a specific section of the light spectrum to which the missing cones are very sensitive.
Deuteranopia (Green Color Blindness ):
In deuteranopia, the green cone cells which are present in the retina are missing or non functional. When a person is having this particular problem, the mixture of green and red colors are being presented in front of that person and will not be able to make out any difference between those colors.
Tritanopia (Blue Colour Blindness ):
A person with tritanopia is deficient in blue cone cells and is not able to distinguish between the yellow and blue colors. This type of blindness is very rare.
Trichromatism:
Trichromatism is a type of color blindness in which all the three types of cells function who perceive light and colors, there used to be a shift in the sensitivity of the wavelengths in one of those colors.
Causes of Color Blindness
It can be caused because of chronic diseases like diabetes, etc.
Color blindness can be caused when the medications are being used for a very long time specially those help in the treatment of the nervous disorders. It can also be caused if any accident has happened and which has caused any damage to the eyes or has restricted the supply of the blood to the eyes. Color blindness can be caused because of the age as it is a part of physical changes.
It is mostly caused due to inheritance. It usually comes from parents. The X chromosome carries the gene which is responsible for color blindness. Due to this, men get more affected.
But some severe accidents, illness, and medication can also cause color blindness. The healthy eye retina of humans consists of rod and cone cells. So if these cells fail to perform then it leads to color blindness. If a person’s eyes have no cones or only one cone, it causes monochromacy.
Dichromacy is caused if one type of cone is missing. When all cones are present but not aligned, it causes anomalous trichromacy in these cases.
How to Check Color Blindness
To measure color blindness in people there are some diagnoses available for them. These tests include the Ishihara plate test and screen testing.
Ishihara Plate Testing:
It is considered to be the most common color vision screening. It is a well-known process that is used in schools and also in eye clinics. In this test, a circle is created with two colored irregular dots. Here, the total plate is 38. In this process, patients have to find the total number on the plates
Screen Testing:
It determines the types of color blindness one is having. The severity of the syndrome is detected by this testing.
Treatment of Color Blindness
To date, no cure has been invented for color blindness. One can use glasses or contact lenses that are available with filters, and it helps in curing color deficiencies if necessary. In daily life, people with red and green color blindness can face a few problems like choosing fresh vegetables, fruits, etc.
Most color-blind people’s vision is normal; all they require is a certain adaptation. People who have this syndrome can follow a properly balanced diet.
Symptoms of Color Blindness
The child can have a difficulty in choosing the red and green color crayons or pencils.
In coloring activities, the child pays less attention or patience towards it.
The child uses the wrong colors in the coloring workbooks.
The child denies any decisions which are based on any colors.
The child is showing a lack of interest in the activities which are related to color.
The color discrimination of the child gets worse when the light is dim.
Some children may also have sensitivity to the bright lights.
FAQs on Understanding Color Blindness: Key Facts for Students
1. What is color blindness, and how does it occur from a biological perspective?
Color blindness, also known as color vision deficiency, is a condition where a person is unable to see colors in the normal way. It occurs due to a problem with the color-sensing cells in the eye's retina, called cone cells. These cells contain light-sensitive pigments (photopigments) that react to different wavelengths of light, allowing us to perceive red, green, and blue. In most cases, color blindness is a genetic condition where the genes responsible for producing these pigments are faulty, leading to an inability to distinguish between certain colors, most commonly red and green.
2. What are the main types of color blindness that a student should know about?
The main types of color blindness are categorized based on which cone cells are affected. The most common types include:
- Red-Green Color Blindness: This is the most prevalent form and includes Deuteranopia (difficulty seeing green) and Protanopia (difficulty seeing red). Individuals find it hard to distinguish between shades of red and green.
- Blue-Yellow Color Blindness (Tritanopia): This is a rarer type where individuals have trouble distinguishing between blue and green, and between yellow and violet.
- Complete Color Blindness (Achromatopsia): This is an extremely rare condition where a person cannot perceive any color at all and sees the world only in shades of grey, black, and white.
3. Why is color blindness significantly more common in males than in females?
The reason lies in genetics. The genes responsible for red-green color blindness are located on the X chromosome, making it an X-linked recessive trait. Males have one X and one Y chromosome (XY). If their single X chromosome carries the recessive gene for color blindness, they will express the trait. Females have two X chromosomes (XX). For a female to be colorblind, she must inherit the recessive gene on both of her X chromosomes, which is statistically much less likely. A female with one affected X chromosome is a carrier but typically has normal vision.
4. Is the gene for common color blindness a dominant or recessive trait?
The gene for the most common form of color blindness, red-green color deficiency, is a recessive trait. This means that for the condition to be expressed, an individual must either have the recessive allele on their only X chromosome (in the case of males) or on both of their X chromosomes (in the case of females). A dominant allele for normal color vision on just one X chromosome is sufficient to prevent the condition in females.
5. Does having color blindness mean a person sees the world only in black and white?
This is a common misconception. Most people with color blindness do not see the world in black and white. Instead, they perceive a limited range of colors. For example, someone with red-green color deficiency might see reds and greens as muted shades of brown or grey, while still being able to see blues and yellows clearly. Only those with the extremely rare condition called achromatopsia see in true black, white, and shades of grey.
6. How can color blindness affect a student's learning in the classroom?
Color blindness can present several challenges for students. For instance, a student may have difficulty:
- Reading color-coded graphs, charts, and maps in subjects like Science, Geography, and Maths.
- Understanding educational materials where color is used to convey information, such as highlighting key terms.
- Participating in art classes that require accurate color mixing and identification.
- Distinguishing between colors in chemical titration experiments or while identifying specimens in Biology.
Teachers can help by using patterns, labels, and high-contrast combinations instead of relying solely on color.
7. Can inherited color blindness be cured or treated?
As of now, there is no cure for inherited color blindness because it is a genetic condition rooted in a person's DNA. However, there are ways to manage the condition. Some people find that special filtered lenses or glasses can enhance the contrast between certain colors, making them easier to distinguish. Additionally, various mobile and computer applications are available that can help identify colors in real-time. It is important to note that these are aids and do not correct the underlying vision deficiency.
8. What is the basic principle behind the Ishihara test used to diagnose color blindness?
The Ishihara test works on the principle of pseudoisochromatic plates. Each plate consists of a pattern of dots of various colors, brightness levels, and sizes. Within the pattern, a number or a shape is embedded using dots of a color that a person with color blindness will confuse with the background dots. A person with normal color vision can easily distinguish the number from the background. However, someone with red-green color deficiency will either be unable to see the number or will see a different number, revealing the nature of their color vision deficiency.
