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- What causes color blindness?
- Causes and factors that contribute to color blindness
- How is color blindness diagnosed?
- Is color blindness treatable?
- Can color blindness be prevented?
Color blindness
Color blindness, or color vision deficiency, is a condition in which the perception of some colors is distorted from their true colors, causing the person to be unable to see those colors clearly or to be confused about the differences between shades of colors. While the term "color blindness" often implies seeing in black and white, the majority of people with color blindness can see a range of colors and have normal eyesight and vision. However, they cannot distinguish between some colors or shades of the colors, such as those with red-green color blindness, who struggle to differentiate between red, green, orange, and brown. The much less common blue-yellow color blindness affects how a person perceives blue and yellow hues, often leading to confusion between blue and green or yellow and gray. Color blindness affects approximately 8% of males and 0.4% of females in the general population worldwide.
What causes color blindness?
Color blindness is caused by a defect in the specialized light-sensitive cells in the retina called cone cells. There are three types of cones: S-cone, M-cone, and L-cone, each sensitive to different wavelengths of light: short (blue), medium (green), and long (red). Color vision is normal when functional cone cells transmit neural impulses to the brain, which then integrates the signals and interprets them as shades of color.
Individuals with color blindness may have defective cones in one, two, or all three types of cone cells, resulting in aberrant color vision, an inability to see colors clearly, or an inability to distinguish certain shades of color, such as those with red-green blindness, who will be unable to distinguish between shades of green, red, orange, or brown. In the rare instance of absent photopigments in the cone cells, which will cause total color blindness (achromatopsia), an individual only sees things in black and white and shades of grey.
How many types of color blindness?
Color blindness is classified into 2 types:
- Congenital color vision deficiency, also known as hereditary color blindness (congenital color vision defect), is the most common type and the most common cause of color blindness. This type of color blindness, most commonly red-green color blindness, is more common in men than women.
- Acquired color vision deficiency is less common than congenital color blindness. This type of color blindness is secondary to abnormalities of the retina or optic nerve, which can be caused by side effects from medications, chemical substances, or traumatic injuries, and frequently result in blue-yellow color blindness.
How many levels of color blindness?
Color blindness is classified into 3 levels:
- Mild level of color blindness: There is some distortion in color vision or the distinctness of hues at this level. Individuals, however, can correctly name the color.
- Moderate color blindness: less ability to distinguish colors, confusion, and uncertainty about naming the colors.
- Severe color blindness: Sees everything in shades of black and white and is unable to perceive colors.
Causes and factors that contribute to color blindness
- Congenital color blindness or genetic color blindness
- Aging leads to the deterioration of various retinal cells.
- Eye diseases such as age-related macular degeneration (AMD), cataract, and glaucoma
- Some diseases, such as diabetes, multiple sclerosis (MS), alcoholism, Parkinson's disease, and Alzheimer's disease
- An eye injury or an accident that affects the eyes
- Side effects of certain medications, such as tuberculosis drugs, autoimmune disease medication, and neurologic medication
- Exposure to certain chemicals, such as styrene monomer (SM), plastics, or foam mixtures
- Welders are exposed to metal welding sparking lights for an extended period of time
Example of Ishihara color test plates. The test taker with normal color vision should clearly see the numbers 12, 33, 38, 51, 69, and 74
How is color blindness diagnosed?
The ophthalmologist will diagnose color blindness in conjunction with multiple tests to check if color blindness exists, classifying the type and severity level of color blindness using the international standard screening test, Ishihara plates. Each test will have hidden colored numbers or lines matching the color-blind individual's defect. If the test taker is unable to read numbers or the lines of the defective colors, the test taker likely has color blindness. The procedure to determine color blindness by an ophthalmologist is as follows:
- For screening color blindness testing, the ophthalmologist uses Ishihara test strips by asking the test subject to read numbers or lines of colors that people with color blindness cannot see.
- If the test taker fails the first test, they will take the Farnsworth-Munsell D-15 Hue Test to assess the efficiency of the eyes in color classification. The test taker will try to line up shades of colors in succession. This method can help diagnose color blindness and also quantify the severity level of color blindness as mild, moderate, or severe.
Is color blindness treatable?
Currently, there is no cure for congenital or hereditary color blindness. However, individuals diagnosed with color blindness can live a regular life in society. A color blindness diagnosis helps inform parents, guardians, and children to make the appropriate career plan.
- In children with color blindness, if the parents or guardians notice an abnormality in their child's color vision or suspect that the child has color blindness, the child should be brought to an ophthalmologist to take the screening test for color blindness.
- Individuals experiencing color vision blindness due to medication side effects should contact their prescribing doctor as soon as possible for medication adjustment in order to alleviate the symptoms of color blindness and prevent the condition from worsening.
- Individuals who have acquired color vision blindness as a result of an accident or a concussive injury in the eye, or who have an abnormal color vision for an unknown cause, should see the ophthalmologist as soon as symptoms appear to find the cause and receive appropriate treatment.
Can color blindness be prevented?
There are ways to prevent acquired color blindness by screening for eye health and color blindness annually or as recommended by an experienced ophthalmologist. Color blindness eye screening can be performed on children as early as 5-6 years old or older. Just before starting school, a child's vision should have an eye checked at least once.
This is to help children to gradually learn and adapt if color blindness is diagnosed. This screening will help children to understand their condition, learn to adapt, and plan for their future.
- Those with congenital color vision deficiency, familial color blindness, or soon-to-be married couples can reduce their risk of passing color blindness genes to their offspring by having advanced eye screening or a pre wedding checkup before marriage and discussing the possibility of a safe pregnancy with a knowledgeable doctor.
- Those with a family history of color blindness should undergo eye screening and color vision testing annually.
- Individuals who do not have congenital color vision deficiency or do not have a history of color blindness in their family should continue to observe their color vision. If color distortion is present, an early diagnosis with an experienced ophthalmologist is advisable as soon as possible.
- Avoid using food containers made of hazardous chemicals.
- Welders exposed to bright light for extended periods of time should wear robust and safe light protection equipment and have regular eye examinations as prescribed by an ophthalmologist.
Color Blindness: Early Screening, Aids Optimal Future Planning
Color blindness is a condition that impacts daily life. Color blindness in children causes the distorted perception of different colors and affects learning, whereas color blindness in adults restricts them from choosing some occupations where color plays an important role in work, such as pilots, graphic designers, fashion designers, chemists, or painters. In cases of severe color blindness, it can affect the ability to distinguish differences between traffic signals, which are important for road safety.
Ophthalmologists, therefore, recommend an eye exam and color vision screening annually, starting from preschool age, to help individuals with color blindness adapt to their daily lives optimally.
