Red blindness

Introduction Red blindness is also known as the first color blindness. The patient is mainly unable to distinguish red, and cannot distinguish between red and dark green, blue and purple, and purple. Often, green is considered yellow, purple is seen as blue, and green and blue are mixed into white.

Cause

The root cause of color blindness is caused by the fact that the primary colors enter an equal state. Among the three primary colors of red, green and blue, if two primary colors enter the same state, it will cause people to lose the "partial" color sense and become a part of the color blind; if there are three primary colors into the same state If you do, you will lose the "all" sense of color and become a full-color blind person. So, under what circumstances can there be two primary colors entering an equal state? Obviously, when the attenuation network in two channels (referred to as "intermediate network" composed of bipolar cells and ganglion cells, etc.) has the same When the attenuation characteristics (that is, when they have the same structure), the primary colors produced by the two channels will be equal. Based on this principle, we propose a partial color blind visual mechanism: if it is due to genetic disease If the attenuation network in a channel structure chooses the structure of another channel, it will cause partial color blindness. Based on the above theory and combined with the basic characteristics of red blindness, we propose that if it is due to genetic disease If the attenuation network in the red channel structure is wrong, the structure of the green channel is chosen, which will cause red blindness.

an examination

(1) medical history

Generally, congenital color blindness has many symptoms, which are usually found during routine color vision examination in physical examination. Due to genetic factors, you should ask about family history in detail.

If the patient complains of visual impairment and has a history of optic neuropathy, he should pay attention to color vision examination, often with color vision disorder.

(two) red and green blind physical examination

Eye examination should pay attention to routine examinations such as vision, pupil, fundus, and visual field. In particular, fundus examination, to understand the condition of optic neuropathy, to help diagnose the secondary color vision disorder.

There are many methods for red blind examination, but they are all primary inspection methods.

False color map

Often referred to as color blindness. It is currently the most widely used inspection method. It uses patterns of colors, letters, letters, or curves that are confusing with the same shades of color. Normal people are identified by color, while those with color blindness are judged by light and dark.

2. Colored velvet group selection method

In a pile of woolen yarns mixed with various colors, the examinee picks a similar color from a certain color.

3. Color vision mirror

Using the principle of proper mixing of red and green light into yellow light, the amount required for red-green light matching is recorded to determine the red-green dysfunction. Can be quantitative, easy for clinical observation and scientific research applications.

(3) Red and green blind device inspection

In order to clarify the detailed diagnosis of optic neuropathy, fundus fluorescein angiography and electrophysiological examination are feasible. It is also possible to further identify intracranial lesions causing color vision disorders by CT scanning or the like.

Differential diagnosis

Color blindness and color weakness are how to determine color blindness and color weakness. Most of the inspections are based on subjective inspection. Generally, they are performed under bright 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 spectroscopy instrument 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-green sensation. This method can be qualitative. It can be quantified. Differential Diagnosis of Color Blindness and Astigmatism Astigmatism refers to an eye disease caused by the unevenness of the surface of the cornea or lens of the eyeball after the light reflected by the object passes through the uneven surface. Regular astigmatism can be corrected with a circular correction lens. Irregular astigmatism caused by uneven or abnormal shape of the cornea can be corrected by contact lenses (or contact lenses), but it must be worn in a scientific way, otherwise it will cause adverse consequences. Color blindness refers to the lack of normal color vision impairment. Most color blindness is a congenital defect. Color blindness can be divided into full color blindness and partial color blindness. Full-color blind people can only distinguish between light and dark, and can't distinguish colors at all. Some color blind people appear to be unable to distinguish a certain color. For example, the red blind can't distinguish red (red is black). Green blinds cannot distinguish between green and color between green and red, and between green and blue. Clinically referred to as red-green blindness. Color-blind patients are not suitable for jobs that require color discrimination.

Diagnosing its basic characteristics, we describe it in four ways:

1. Highlight characteristics: The bright spot refers to where the brightest part of the scene occurs when people observe the spectrum. When the normal color vision is observed, the position of the bright spot occurs at 555 nm. However, when the red blind person observes the spectrum, the position of the bright spot is shifted. It is shifted in the direction of the short wave by about 540 nm.

2. Spectral length characteristics: When the red blind person observes the spectrum, there is an invisible place near 700 nm. That is, the red blind has a blind zone around 700 nm. In this way, the spectrum of the red blind spectrum is shorter than the normal color vision.

3. Neutral point characteristics: When the red blind person observes the spectrum, there is only one neutral color and no color. This place is called the neutral point. The red-blind neutral point occurs around 480 nm.

4, color discrimination features: red blind people can only see yellow and blue when viewing the spectrum. Common 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 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 spectroscopy instrument 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-green sensation. This method can be qualitative. It can be quantified.

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