Ishihara

Ishihara refers to a color vision test developed by Shinobu Ishihara in 1917. It uses a series of pseudoisochromatic plates—dot patterns of varying colors and brightness—that contain figures such as numbers or paths. People with normal color vision can discern the figure, while many with red-green color deficiencies cannot. The test is primarily used to identify red-green color blindness and to screen for color vision problems in ophthalmology, optometry, education, and military contexts. Common versions include a 38-plate set and a shorter 24-plate version; digital and regional adaptations exist.

Administration is quick and simple, usually under standardized lighting; however results can be affected by lighting, plate quality, and color-naming ability. It is not a definitive diagnostic instrument for color vision deficiency or its severity. It is less reliable for diagnosing blue-yellow deficiencies, and some color-blind individuals may perform within normal limits.

Ishihara is a Japanese surname. Notable individuals include Shinobu Ishihara, the ophthalmologist who devised the color vision test, and Shintarō Ishihara (1932–2020), a Japanese writer and politician who served as Governor of Tokyo.