Iridology is a method of understanding a person's state of health by examining his or her eyes. It can play a role in the diagnosis and prevention of complaints like migraine, as well as illnesses and diseases where early diagnosis can be of enormous benefit including diabetes, multiple sclerosis and kidney problems. Emotional and mental problems can also be detected. This guide, which is part of a series, outlines what iridology is and how it works, what it can be used for and where to find out more, and includes basic iridology techniques for self-diagnosis.