a test consisting of pseudoisochromatic charts containing dots of various hues, saturations, and intensities developed for the detection of abnormal color perception. Some of the dots form numbers that are visible to the normal eye but not to the color-blind or color-weak eye. Now obsolete, it is the predecessor to the commonly used Ishihara Test for Color Blindness. [developed in 1877 by German ophthalmologist Jakob Stilling (1842–1915)]