Weak green

Introduction Partial color weakness is red weak (first color weak), green weak (second color weak) and blue yellow weak (third color weak), among which red and green are weaker, patients have poor red and green sensation, and when lighting is poor, The color discrimination ability is close to red and green blindness; but when the material color is dark, clear and the illumination is good, the color discrimination ability is close to normal. A. Fick believes that the patient's retina also has two kinds of pyramidal cells that normal people feel red and green, but the information from these two cells is mixed together, so the brain can't distinguish it from red light. , or green light.

Cause

Color blindness and color weakness are collectively called color vision disorders, which are divided into two categories: congenital and acquired. Congenital color vision disorder is most likely to be red-green blind, and this color blindness is a genetic disease, which is through recessive inheritance. That is, men with color blindness pass the genetics (X chromosome) to their grandson (male) generation through their daughters. That is to say, the grandfather shows red-green blindness, which is passed on to the daughter but the daughter does not appear to be color blind but with genetic factors. Her son, the grandson, showed color blindness. Only the mother who gave birth to the color vision disorder gene and the daughter born to the father with color blindness showed excellent blindness. Therefore, the incidence of male blindness in the crowd is higher than that of females, which is five times higher than that of females.

Congenital color blindness or color weakness is a hereditary disease and is related to gender. Clinical investigations show that male color blindness accounts for 4.9%, female color blindness only accounts for 0.18%, and the number of male patients is much higher than that of females. This is because the color-blind genetics are present on the X chromosome of the sex chromosome and adopt the concomitant recessive inheritance. Usually men are characterized by color blindness, while women are carriers of color-blind genes with normal appearance, so color-blind patients are more male than female.

an examination

Related inspection

Farnsworth 15 color standard test FM-100 color test Nagel color vision examination ophthalmology eye function test

Color blind (weak) patients are born with no correct color discrimination ability, and think that others are the same as themselves, so they can not be consciously sick, and many color blind patients have no abnormal findings in eye examination.

Most of the color blindness and color test are subjective inspections, which are generally performed under brighter natural light. The commonly used inspection methods are as follows.

False homochromatic map: commonly referred to as a color-blind book, which uses dots of the same shade and different colors to form numbers or figures, and reads at a distance of 0.5 m under natural light. The color blindness should be corrected when checking, and each figure should not exceed 5 seconds. Color vision disorders are difficult to identify, misread or impossible to read, and can be confirmed according to the color blindness table.

Color Harness Test: It is a mixture of different shades of yarns of different colors, so that the examinee picks out the same color bundle as the standard harness. This method is quite time consuming and can only be qualitatively and cannot be quantified, and is not suitable for large-area screening tests.

Color Mixing Tester: It is a kind of spectrometer designed by nagel based on the principle of red + green = yellow. It can quantitatively record the amount of red and green light matching to determine the red and green anomaly. This method can be qualitative. It can be quantified.

Differential diagnosis

The whole color is weak, also known as red, green, blue and yellow. The color vision disorder is lower than the full color blindness, there is no abnormality in visual acuity, and there are no other complications of full color blindness. When the object is dark and vivid, it can be distinguished; if the color is shallow and not saturated, it is difficult to distinguish. Patients are also rare.

Partially weak

There are red weak (first color weak), green weak (second color weak) and blue yellow weak (third color weak), among which red and green are weaker, patients are less sensitive to red and green, and when lighting is poor, The color ability is close to red-green blindness; but when the material color is dark, clear and the illumination is good, its color discrimination ability is close to normal. Color blind (weak) patients are born with no correct color discrimination ability, and think that others are the same as themselves, so they can not be consciously sick, and many color blind patients have no abnormal findings in eye examination.

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