How to test for color weakness

Color vision deficiency is primarily detected through the following methods: 1. Pseudoisochromatic plate test: The subject is required to identify patterns on specialized color plates. Inability to accurately recognize these patterns may indicate color weakness. This method is simple and straightforward, typically involving patterns or numbers composed of dots in different colors to test color vision. 2. Hue arrangement test: Under standardized lighting, the subject must sort objects or cards of various shapes and colors according to hue. The examiner evaluates the nature and severity of any color vision deficiency based on the sorting sequence. 3. Farnsworth D-15 or Munsell test (colored yarn sorting): The subject is asked to select from a mixed set of colored yarns those matching a standard reference in both color and shade. Difficulty in accurately identifying matching yarns may suggest color weakness. 4. Color mixing apparatus: A spectral instrument that detects color deficiency by quantitatively measuring the amounts of red and green light required for color matching.