Ishihara graduated from medicine in 1905 on a military scholarship[1] and immediately joined the Imperial Japanese Army as a doctor, serving mainly as a surgeon.

The name Ishihara is known worldwide because of the color vision test he published in 1917,[2] where a subject is shown a coloured pattern and asked what numerals they see there.

Ishihara also developed a Japanese visual acuity chart and an apparatus for determining the near point, both currently in wide use in Japan.

Ishihara was appointed the professor and chairman, to succeed Komoto, at the Ophthalmology Department of the Imperial University of Tokyo in 1922 and served until March 1940.

As was the custom in those days, patients left tokens of their gratitude in home-grown produce and small sums of money.