Color blindness: what it is, causes and symptoms

Approximately one in ten men has some form of color blindness, a visual inability to distinguish certain colors, which has a genetic origin linked to the X chromosome.

What is color blindness?

This alteration owes its name to the English scientist John Dalton, who was the first described case of color blindness. Color blindness is a visual disability that prevents you from distinguishing certain colors. This is due to the lack or malfunction of one or more than one type of cone.

Also known as color deficiency. In color blindness, the person generally cannot distinguish between certain colors. They often do not distinguish green from red, and sometimes blue.

In the retina There are two types of cells that detect light. These cells are called swabs and cones. Rods only detect light and dark and are very sensitive to low levels of light. The 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 different color 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 is not working well. Detects a different color than normal.

There are different degrees of color blindness. Some people with mild color vision deficiencies detect colors normally in good light but have difficulty in dim light. Others cannot distinguish certain colors in any type of 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.

You are usually 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 the presence of a more serious problem. Anyone who notices a change in the way they perceive colors should consult a doctor. 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. Making a rough classification, three types of color blindness can be distinguished:

Dichromatism

The most common form is dichromatism, which affects the cones responsible for capturing red or green . If one of the cell types is missing, the other will be in charge of 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 establishing the difference 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 trichromatism

Another form of color blindness that has similar, although milder, effects than the previous two cases. In this case, the individual It has the three types of cones , but there is some deficiency in them that prevents completely normal functioning.

Achromatopsia

Finally, the most serious case of color blindness is the so-called achromatopsia, as a result of which the individual who suffers from it only notices differences in the grayscale .

Causes of color blindness

This alteration has a genetic origin ; It is a disorder of sex-linked inheritance, that is, the affected gene is found on one of the sex chromosomes (human beings have 46 pairs of chromosomes of which 22 pairs are autosomal and one pair is sexual).

In this case it is a recessive gene linked to the X chromosome; This means that all men who inherit an both parents carried said gene). This explains why cases of color blindness in women are rare, while approximately one in ten men has some form of color blindness.

Most color vision problems that appear later in life result from:

an illness
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 symptoms so mild that they do not realize they have color deficiency or do not see colors well. Sometimes parents notice a problem only when the 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 happens mostly between red and green or between blue and yellow.