Medical Diagnostic Criteria for Color Blindness and Color Weakness

The medical diagnostic criteria for color blindness and color weakness generally require analysis based on test results from pseudoisochromatic charts, anomaloscopes, and hue arrangement methods.

1. Pseudoisochromatic Charts

Pseudoisochromatic charts typically consist of images formed by dots of the same brightness but different colors, or dots of the same color but varying brightness. Under normal circumstances, individuals with color blindness may rely on differences in lightness or darkness to interpret the images. For example, under natural white light and at a viewing distance of approximately 50 cm, if a person can correctly identify the colors within five seconds, their color vision is considered normal. A prolonged identification time suggests color weakness, while an inability to distinguish colors indicates color blindness.

2. Anomaloscope Examination

Anomaloscope testing primarily relies on the principle of color mixing. By adjusting the proportions of two colors to match a target color, this method helps determine the type and severity of color vision deficiency.

3. Hue Arrangement Method

This test is usually conducted under natural lighting or standardized illumination, examining each eye separately. Patients are asked to arrange colored caps according to the rules of color transition and sequence. The examiner records the serial numbers marked on the caps, plots a trajectory diagram, and calculates the total error score to determine whether color blindness or color weakness is present.

It is recommended that, in daily life, individuals appropriately consume foods rich in vitamin A, vitamin C, and riboflavin, which may help prevent color blindness and color weakness.