What is color blindness?
This disorder is named after the English scientist John Dalton, who was the first described case of color blindness. Color blindness is a visual disability that prevents one from distinguishing certain colors. This is due to the absence or malfunction of one or more types of cones.
It's also known as color deficiency. In color blindness, the person generally can't distinguish between certain colors. They often can't distinguish between greens and reds, and sometimes between blues.
In the retina There are two types of cells that detect light. These cells are called cotton swabs and Cones. Rods detect only light and dark and are very sensitive to low light levels. Cones detect colors and are concentrated near the center of vision. There are three types of cones: some detect red, others green, and others blue. The brain uses the information sent by the cones to determine the color we perceive.
Color blindness can occur when one or more types of cones are absent, do not function, or detect a color different than normal. Severe color blindness occurs when all three types of cones are absent. Mild color blindness occurs when all three types of cones are present, but one of them does not function well. It detects a color different than normal.
There are different degrees of color blindness. Some people with mild color deficiencies detect colors normally in good light but have difficulty in dim light. Others cannot distinguish certain colors in any light. The most severe form of color blindness, in which everything appears in different shades of gray, is rare. Color blindness usually affects both eyes equally and remains stable throughout life.
Color blindness is usually present in people born with color blindness, but in some cases it can be acquired later in life. A change in the way you see colors may indicate a more serious problem. Anyone who notices a change in the way they perceive colors should consult a color specialist. ophthalmologist.
Types of color blindness
There are multiple variants of this disorder; in fact, it could be said that no colorblind person sees exactly the same as another. Roughly categorized, three types of colorblindness can be distinguished:
Dichromatism
The most common form is dichromatism, which affects the cones responsible for capturing light. Red or green . If one of the cell types is missing, the other will be responsible for collecting the stimuli that would correspond to the first; thus, in many cases, the two incoming stimuli will be perceived as the same color. People with this type of color blindness have difficulty distinguishing between the colors red and green.
Another variant of this disorder is the lack of the cones responsible for capturing the blue tones ; in this case, individuals will frequently confuse the colors blue and yellow. These types of color blindness are called dichromatism, since the individual has only two types of cones.
Anomalous trichromatismAnother form of color blindness that has similar, though milder, effects than the two previous cases. In this case, the individual It presents the three types of cones , but there is some deficiency in them that prevents completely normal functioning.
AchromatopsiaFinally, the most serious case of color blindness is the so-called achromatopsia, as a result of which the individual who suffers from it only sees differences in the grayscale .
Causes of color blindness
This alteration has a Genetic origin ; this is a sex-linked inheritance disorder, meaning the affected gene is located on one of the sex chromosomes (humans have 46 pairs of chromosomes, of which 22 pairs are autosomal and one pair is sexual).
In this case, it is an X-linked recessive gene; this means that all men who inherit an X chromosome with the defective gene will suffer from the disorder, while women will only suffer from it if both chromosomes carry the gene (which is quite unlikely, as it would require both parents to carry the gene). This explains why cases of color blindness in women are rare, while approximately one in ten men have some form of color blindness.
Most color vision problems that appear later in life are a result of:
- a disease
- a trauma
- the toxic effects of some medications
- a metabolic disease or
- a vascular disease
Symptoms of color blindness
The symptoms of color blindness can range from mild to severe. Many people have such mild symptoms that they don't realize they have color deficiency or that they don't see colors well. Sometimes parents notice a problem only when their child is learning colors.
Symptoms include:
- Difficulty seeing colors and their brightness in the usual way
- Not being able to tell the difference between different shades of the same color or between similar colors. This occurs most often between red and green or between blue and yellow.
