Color blindness is usually an inherited condition caused by abnormalities in the genes that produce the pigments responsible for color vision. There are different types of color blindness, including red-green color blindness, blue-yellow color blindness, and total color blindness. People with color blindness may have difficulty distinguishing between colors, especially red and green, and may see some colors as shades of gray.

To test for color blindness, there are several methods, including the Ishihara test, the Farnsworth-Munsell 100 Hue test, and the Nagel anomaloscope test. These tests involve the use of color plates or lights that are designed to reveal the type and severity of color blindness.