Loss of color vision

Introduction According to the theory of three primary colors, the color discrimination that loses one color is called dichromatic vision, and the loss of red color discrimination is called red blindness. The red end of the human spectrum is shortened, the red sensitivity to the spectrum is reduced, and it is seen as a dark color. He drives a red light, often because the red light is not bright enough for him. The loss of green color discrimination is called green blindness. Yellow blue is less blind. The ability to lose color in two colors is called a color vision, also known as full color blindness, only the distinction between light and dark. Full color blindness can be divided into typical and atypical.

Cause

Color vision abnormalities can be divided into two categories: congenital color vision abnormalities and acquired color vision abnormalities.

Congenital color vision abnormalities: In 1986, Nathans et al. confirmed from the molecular biology point that the human red-green sense gene is located on the X chromosome, while the blue sense gene is located on the seventh pair of autosomes. The abnormality of color vision is caused by the unequal exchange and recombination of genes.

Abnormal color vision abnormalities: Acquired color vision abnormalities can be caused by eye diseases, systemic diseases, nervous system diseases, chemicals, drugs or age factors.

Kollner first proposed that retinopathy is mainly caused by yellow and blue obstacles, while optic nerve diseases are characterized by red and green obstacles.

an examination

Related inspection

FM-100 color test, homochromatic check, Nagel color vision

1 color table check method

The fake color table is usually called the color blind checklist. There are Shiyuan Ren and Stilling fake color table in foreign countries. There are Yu Ziping and Jia Yongyuan color blind check charts in China. The design principle is that the dots are composed of dots with the same brightness and darkness (the degree of shade) and each color is composed of dots of one color to form numbers, letters, patterns or curves, and dots of other colors are used. Form the bottom of the map. A normal person recognizes a figure by color rather than brightness, so that a correct judgment can be made, and an abnormal color vision is recognized by brightness instead of color, so that a correct judgment cannot be made. The other picture is composed of dots with the same color and different brightness, which can not be recognized by normal people, and can be recognized by people with abnormal color vision. At present, this method is still used as a screening method to separate normal people from those with abnormal color vision.

2 FM-100 color test

The Fornsworth-munsell-100 color tester consists of 93 different wavelength plates (wavelengths from 455 to 633 nm), packaged in 4 wooden boxes, each with a fixed color wheel at each end for color matching. The remaining color plates can be moved.

The inspection method is that under fixed illumination, the inspectors arrange the color discs in order according to the color change rule, and each box is limited to 2 minutes, and the number on the back side of the small box is recorded on the record sheet, and the score is recorded. The pattern of the normal eye is a circular ring pattern close to the inner ring; if it is not normal, in the difficult part of color discrimination, the figure is outwardly displaced into a gear shape.

The FM-100 color test can be used as a color vision anomaly and quantitative analysis.

3 Farnsworth15 color standard test

The inspection instrument is installed in a tweezers with 15 color standards. The inspection method is basically the same as above, and it is required to arrange 15 color standards within 2 minutes.

As a result, it is judged that, for example, the color scales 1 to 15 are all correctly arranged or the order of the adjacent two color patches is reversed to pass; if the arrangement order is disordered, it is a failure. The results are plotted to determine if the color vision is abnormal.

The inspection method is simple and accurate, and the type and degree of color vision abnormality can be measured.

4 Nagel color vision examination

The color vision mirror is a spectroscopic instrument designed according to the principle that red light and green light are properly mixed into yellow light. From the eyepiece, the circular field of view has a yellow light in the lower half and an adjustable red and green light in the upper half.

Differential diagnosis

Loss of color vision needs to be identified as follows:

Weak color: low ability to recognize colors, medically known as color weakness;

Color blindness: The color is completely unrecognizable, medically known as color blindness.

In addition to the human eye, you can feel the intensity of light, and you can distinguish different colors. This ability to distinguish colors is also the color perception. If you lose this ability, it is often called color blindness. If this ability is weak, it is weak. .

The material in this site is intended to be of general informational use and is not intended to constitute medical advice, probable diagnosis, or recommended treatments.