Anomaloskope

Anomaloscope is a device used in color vision testing. It is designed to assess an individual's ability to perceive and distinguish between different shades of red and green. The instrument works by presenting a mixture of red and green light, which the subject is asked to adjust to match a standard yellow light. The deviations from the standard setting indicate the type and severity of red-green color deficiency, also known as deuteranopia or protanopia.

The anomaloscope typically consists of a viewing box with adjustable light sources. A central field of light is presented, which the subject manipulates by controlling the intensity of red and green components. This mixed field is then compared to a reference field of yellow light. The observer's task is to make the mixed field appear identical in hue and brightness to the reference yellow field. The degree to which the subject can achieve this match provides a quantitative measure of their red-green color vision.

The results obtained from an anomaloscope test are often expressed as a ratio or a numerical score, which helps in classifying the color vision defect. This device is particularly useful in occupational settings where accurate color discrimination is critical, such as aviation, driving, and certain medical professions. It is considered a standard tool for comprehensive color vision assessment.