The eye may have color vision disorders called "dyschromatopsia". The most common form is color blindness.
It should be noted, however, that color blindness only corresponds to the hereditary aspect of color vision anomalies. The other aspect concerns acquired deficiencies in color perception.
1- Normal color vision:
The eye is capable, thanks to 3 types of specific retinal cells called cones, of perceiving the fundamental colors red, green and blue.
These signals are then transmitted by the optical pathways to the brain in the form of messages coded by antagonistic red-green and blue-yellow pairs.
The brain then develops the colored sensation at the level of the visual cortex and then other brain centers make us aware of the colored perception.
2- Hereditary dyschromatopsia: color blindness
The different forms of color blindness:
The color blind person does not have the 3 normal channels to form colors.
– either one of the channels is absent, then the color blind person is "dichromate", he only forms colors using 2 channels.
- if red is missing, the subject is called protanope,
- if green is missing, it is deuteranope (the most common),
- if blue is missing (extremely rare), it is tritanope.
– either one of the channels is present but deficient, the color blind person is then an “abnormal trichromat”:
- if red is deficient, it is called protanomaly,
- if it is green, it is deuteranomalous,
- if it is blue, it is tritanoma.
The color blind person's handicap:
The greater the anomaly, the greater the discomfort of the wearer.
In the abnormal trichromat, the errors are barely visible in everyday life. On the other hand, in the dichromat, there are significant color confusions that make him totally unfit for any professional task with a strong color implication.
It is common to say that color blind people confuse green with red, in reality, their perception of the colored world is very far from that of the normal trichromat in the sense that their environment has only two dominant colors (usually blue and yellow), but with a large number of shades.
The transmission of color blindness:
In the two most common forms (red and green deficiencies), the transmission of the anomaly is hereditary and passes through the X sex chromosome.
We can therefore perfectly statistically predict the risks incurred by the descendants of dyschromatic subjects and find carriers of the deficient genes in their ancestors.
In France, the proportion of color blind people is approximately 8% in men and 0.45% in women.
Screening and Professional Impact:
It is important that young people with color blindness know about their anomaly before the decisive phases of their educational and professional orientation, as certain professions are closed to them (for example, we can cite the professions of airline pilot, air traffic controller)
This screening is often done by school medicine using colored plates called pseudo isochromatic, intended to "trap" the deficit. However, only the Ophthalmologist has the means and skills necessary for the qualitative and quantitative diagnosis of dyschromatopsia.
This precise diagnosis is the essential prerequisite for sound advice on future professional orientation.
3- Acquired dyschromatopsia
In certain eye or general diseases (glaucoma, diabetes, etc.), color vision can be altered in a way that is often imperceptible to the patient.
The discovery of these anomalies allows the ophthalmologist, in certain circumstances, using specific tests, to make or support a diagnosis.
These anomalies often appear at a very early stage of the disease. Their discovery then allows rapid intervention in the implementation of treatment.
Unlike hereditary dyschromatopsia which is immutable, acquired anomalies are variable over the course of the disease that caused them and are indirectly curable by treating the causal disease (for example in electronics).
Treatment:
There is no treatment for this anomaly yet.
Injecting the deficient gene into the retina of affected monkeys has allowed their color blindness to be corrected.
Source: SNOF
http://www.snof.org/vue/couleurs1 .html
http://www.snof.org/vue/coulanthony.html
To find out more:
fr.wikipedia. org/wiki/Colorblindness
www.daltonisme.com