Ishihara Color Test

Pseudoisochromatic plates for detecting red green color deficiency

Overview

The Ishihara test is a set of plates covered in dots of varying color and size, arranged so that a number or path is visible to people with normal color vision but hidden or different for those with red green color vision deficiency. It was devised by the Japanese ophthalmologist Shinobu Ishihara and first published in 1917. It is widely used for screening in schools, clinics, and occupational settings, but it is designed mainly for red green deficiencies and does not reliably detect blue yellow defects. Arrangement tests such as the Farnsworth D15 and anomaloscopes are used for more detailed classification.