To detect any defects in color perception, Ishihara tables are usually used, where numbers or symbols are hidden within colored dots. Patients with color blindness or acquired vision impairment fail to see some or all of the hidden figures.
To further investigate the anomalies of the chromatic sense, the Farnsworth test is performed, which consists in putting in the correct tonal sequence a series of colored discs.
Most congenital color blindness is red-green; the majority of those acquired - caused, for example, by glaucoma and optical neuropathies - is blue-yellow.
