Ridologen behaupten, dass sie keine spezifischen Krankheiten diagnostizieren, sondern diese “hervorheben” diejenigen Systeme und Organe im Körper, die gesund sind und als solche beschrieben werden “überaktiv” oder “entzündet.” These are said to point to a tendency in the patient towards certain illnesses, to reflect past medical problems, or to predict health problems which may be developing.Since iridology is not a method of treatment, its practitioners have often studied other branches of alternative medicine, such as naturopathy, and used the study of the iris as a diagnostic first step. Iridology is practiced more widely in Europe (especially in the UK and Germany), where there are approximately 20,000 practitioners, than in the United States, which has only a tenth of that number.