The 24 -plate Ishihara color test is composed of a series of colored cards on which numbers or lines of equal shade can be read by a person with normal color vision but not by someone with defective color vision. It makes use of the peculiarity that in red-green blindness, blue and yellow appear remarkably bright compared to red and green. The color plates are encased in specially designed album-type book for ease of handling. It includes 24 special plates for tests to determine the type and degree of defect in color blindness. This color blindness test is accepted by leading authorities.