Ishiharafärgplattor

Ishiharafärgplattor, often referred to as Ishihara plates, are a type of pseudoisochromatic optical instrument used to detect color vision deficiencies, most commonly red-green color blindness. Developed by Japanese ophthalmologist Dr. Shinobu Ishihara, these plates present a series of dotted figures embedded within a background of similarly colored dots. The figure and background are designed to have different color combinations that are difficult for individuals with specific types of color blindness to distinguish.

The plates are typically arranged in a sequence, with some plates designed to reveal a number or pattern to those with normal color vision, while others present a different number or no pattern at all to those with a color vision deficiency. There are also plates that are designed to be confusing for individuals with normal color vision, acting as control plates. The most common version of the Ishihara test consists of 38 plates.

The effectiveness of the Ishihara test relies on the principle of confusion lines, which are color combinations that appear similar to individuals with color vision deficiencies. For example, certain shades of red and green dots might be used to form a number that is invisible to someone who cannot differentiate between these colors. The test is simple to administer and is widely used in ophthalmology, optometry, and by licensing authorities for professions where accurate color perception is critical. While effective for identifying common forms of red-green color blindness, it may not detect all types or degrees of color vision deficiency.