Iridology is the analysis of the iris of the eye to gain health information. It was discovered in the 19th century and involves examining the color, structure, and markings of the iris to interpret indications of health conditions. The iris is divided into zones associated with different body systems. Colors, lines, dots and other signs within the iris are analyzed for what they may suggest about acute, sub-acute, or chronic conditions in related organs and systems. While still being researched, iridology has been studied and practiced through various institutions and practitioners over its history.