Color weakness refers to color visual defects, and those who can recognize colors but have low sensitivity are called color weakness.
Weak color is a mild color vision abnormality, which is more common in men. Patients with weak color have poor ability to distinguish colors, and can only see colors when they are saturated. Red weak (A) and green weak (B) are common, and blue weak is rare.
Diagnostic basis for color weakness:
1. has a family genetic history.
2. Clinical manifestations of poor color discrimination.
3. When the false homochromes are examined, the patients are difficult to identify, and they are misread or cannot be read.
4. The color harness test shows that the patient can't pick out the harness with the same color as the standard harness.
5. The color mixture tester can determine whether the red and green color vision is abnormal.
Expand:
1 and weak color are also called "abnormal trichromatic vision". Color vision defect. Those who can recognize colors but have low sensitivity are called weak colors. Patients with weak color have poor ability to distinguish colors, and can only see colors when they are saturated.
2. Only when the wavelengths are quite different can we distinguish the change of hue. Red and green are more common, and blue is extremely rare. Weak red has poor ability to distinguish red; Weak green has poor ability to distinguish green. The patients with weak color are mostly men.
Second, the inspection method.
1, false homochromatic map: commonly called color-blind book, it uses dots with the same tone depth but different colors to form numbers or figures, which can be read at a distance of 0.5m in natural light. Color blindness should be corrected during the inspection, and each picture should not exceed 5 seconds. People with color vision impairment have difficulty in identifying, misreading or unable to read, and can confirm what kind of color vision abnormality they belong to according to the regulations of color blindness table.
2. Color harness test: mix the wool harnesses with different colors and different shades, so that the examinee can pick out the harness with the same color as the standard harness. This method is time-consuming, and can only be roughly qualitative but not quantitative, so it is not suitable for large-scale screening and inspection.