People with color blindness are born without the ability to properly distinguish colors and assume that others are like them, so they are not aware of the disease. How to determine color blindness and color deficiency? Most of the tests for color blindness and color deficiency are performed by primary sensory examination, usually under bright natural light. The color-blind book should be placed correctly during the examination, and each figure should not exceed 5 seconds. Color vision difficulties, reading the wrong or can not be read, according to the color blindness table to confirm what belongs to the color vision abnormalities. Color bundle test: is a different color, shades of hair bundle mixed together, so that the person being inspected to pick out the same color bundle with the standard bundle. This method is time-consuming, and only roughly qualitative can not be quantitative, not suitable for large area screening inspection. Color mixing tester: is nagel according to the principle of red + green = yellow, designed a spectral instrument, it can quantitatively record the amount of red and green light matching required to determine the red and green sensory abnormalities, this method can be both qualitative and quantitative. Color blindness is divided into total color blindness and partial color blindness (red blindness, green blindness, blue-yellow blindness, etc.). Color vision is divided into full and partial color vision (red vision, green vision, blue vision, etc.).