To test whether a patient suffers from color blindness or color weakness, the more commonly used clinical test is the pseudo-same-color chart, also known as the color blind book.
In the color blindness book, there are diagrams composed of spots with the same brightness and different colors, and there are diagrams composed of spots with the same color and different brightness in the same diagram. People with normal color vision discriminate based on color and the answers are often correct, but color-blind people judge based on brightness and often give incorrect answers.
Checking under natural white light, keeping a distance of 0.5 meters, the person who gives a correct answer within 5 seconds is considered normal, the person who prolongs the time is considered color weak, and the person who can’t distinguish at all is considered color blind. It can also be used to determine the degree and type of color vision impairment by arranging objects of the closest color together under fixed lighting.
It is recommended that patients with color vision abnormalities seek prompt medical attention to evaluate their condition and follow the doctor’s instructions for treatment.