Clinical Briefs-With Comments from John La Puma, MD, FACP

Iridology to Identify Toxins

May 2000; Volume 3; 60

Source: Ernst E. Iridology: Not useful and potentially harmful. Arch Ophthalmol 2000;118:120-121.

More than 1,000 licensed natur-opathic physicians practice in the United States, and iridology is described as "the most valuable diagnostic tool of the naturopath." Some therapists are using iridology as a basis for recommending dietary supplements and/or herbs. Several iridology organizations exist: The National Iridology Research Association is an iridologists’ service organization; the International Association of Iridologists is the leading organization for European-style iridology and runs training programs; and the Bastyr Naturopathic College in Seattle, Wash., has an elective course on iridology (J. Colton, e-mail communication, December 2, 1998). In the United States, insurance programs do not normally cover iridology, but in some European countries, they do. In Germany, for instance, 80% of the Heilpraktiker (nonmedically qualified health practitioners) practice iridology. Ophthalmologists may therefore ask what is iridology and how valuable is it?


Iridology is knowledge about the iris, especially about the connection between its pigmentation and organ dysfunction. Each iris is divided into three major and three minor zones; some iridologists divide the iris, like an hour, into 60 parts; others divide it into 100 parts. Each part relates to an organ or an internal function. Maps of the right iris correspond to the right side of the body; maps of the left iris correspond to the left. Careful photographs of both irides are often taken by iridologists, and examined. Neural connections are responsible for the correlation between the iris and organ function.

Iridology is practiced by some homeopaths and naturopaths. Iridologists do not claim to diagnose particular illnesses, but instead, to identify toxicities and dysfunction. Specific natural remedies can, at an iridologist’s recommendation, prevent illness from developing. If it does, then the credit goes to the iridologist.

Ernst identifies four controlled, masked evaluations of the diagnostic validity of iridology: One study evaluated patients with renal disease, gallbladder disease, ulcerative colitis, coronary heart disease, asthma, pleurisy, gastroenteritis, and an upper respiratory infection. Sample size ranged from 1-146; all trials were small; all involved at least one and two involved several iridologists. All studies, according to Ernst, were adequately designed and masked, and consisted largely of evaluating color photographs of the iris. None found any diagnostic accuracy with iridology.

These data suggest that iridology is a waste of time and money. But how many patients have been reassured that their irideal maps were normal while their real pathophysiology continued to brew? How many patients receive diagnoses of "toxicity" they don’t really have?


The practice of iridology should be thought of as crystal ball reading—what you see is, or is not, what you get. Tell your patients to save their money.