Poor color discrimination is called color weakness, and it is not easy to strictly distinguish it from color blindness, but the degree of severity is different. Color weakness includes total color weakness and partial color weakness (red weakness, green weakness, blue-yellow weakness, etc.). Blue-yellow color weakness is also known as the third color blindness. Patients with blue-yellow confusion, red, green discernible, less common. Blue-yellow weakness is a type of color blindness. The disease requires a differential diagnosis with blue-yellow color blindness. Blue-yellow color blindness: Blue-yellow color blindness is also known as third color blindness. Patients with blue-yellow confusion, red, green can be recognized, less common. People with blue-yellow colorblindness have difficulty recognizing blue and yellow. Blue-yellow colorblindness includes blue blindness (tritanopia, third color blindness) and blue weakness (tritanomaly, third color weakness). Blue-yellow colorblindness is one type of colorblindness.