Color blindness, also known as Dalton's disease, is divided into congenital color blindness and acquired color blindness, congenital color blindness for the sexual chain of inheritance, more men than women, both eyes with normal visual function and color discrimination abnormal. Patients often feel that they have no difficulty in recognizing colors, but it is found during examination. Acquired color blindness is also known as acquired color blindness because it is secondary to some fundus diseases, such as some optic nerve and retinal diseases.
Color blindness refers to the lack or complete absence of the ability to distinguish colors. Usually, color blindness refers to red-green color blindness. Facing the colorful world, how do people perceive it? It turns out that there is a kind of photoreceptor cells - cone cells - in the human retina, which have 3 kinds of photoreceptor pigments, red, green and blue. Each photoreceptor pigment is mainly excited by one primary color of light and reacts to the remaining two primary colors of light to varying degrees. If one of these pigments is deficient, there is an impairment in the perception of that color, which is manifested as color blindness or color weakness (weak color discrimination). There are many different types of color blindness. Those who lack the ability to distinguish only one primary color are called monochromatic blindness, such as red blindness, also known as the first color blindness, which is more common; green blindness, known as the second color blindness, which is less common than the first color blindness; and blue blindness, which is the third color blindness, which is less common. If a person lacks the ability to distinguish between two colors, it is called total color blindness, which is more rare. Color blindness is mostly due to congenital inheritance, and in a few cases it is due to disorders of the visual pathway conduction system. It is usually transmitted by females and manifested by males. According to statistics, the prevalence of color blindness in males is 5% while in females it is 1%. People with congenital color vision disorder often do not know that they have abnormal color discrimination, and it is mostly detected by others or during physical examination. Where engaged in transportation, art, chemistry, medicine and other staff must have normal color vision, therefore, the color vision examination has become a routine project for military service, employment, medical examination before school.