64% of individuals considers that color confusion is the biggest problem.
The name Ishihara is known worldwide because of the Ishihara Color Vision charts which he established in 1918. Even today, his test remains the one of choice throughout the world. Ishihara developed a Japanese visual acuity chart and an apparatus for determining the near point, both currently in wide use in Japan. He also made significant contributions to the study of trachoma and myopia.