by Bob Lloyd

Created on: January 30, 2010

Iridology is a form of treatment based on the assumption that the iris, that coloured part at the front of the eye, contains regions that map to the organs of the body, in such a way that changes detected in the iris demonstrate the condition of those organs.  The iris of the eye is seen as a means of diagnosing medical conditions.

Some iridologists claim that they can detect the medical history of the patient by examining the iris.  Some, such as the American iridologist Bernard Jensen suggested that it was possible to detect changes in the body through nerve reflex responses seen in the iris.

Crucially the claims of iridologists depend on there being a reliable link between the state of the iris and the state of the body.  However, it is known that the state of the iris changes very little during the course of the life and that there is no automatic connection between the iris and the state of the body.  There is no "nerve response" of the kind mentioned by Jensen.

The iris therefore cannot form a reliable diagnostic tool for medical conditions.  This was put to the test with Jensen himself and two other iridologists published in the Journal of the American Medical Association in 1979.  Jensen and the others were asked to identify from photographs of the eyes of 143 people, which ones had kidney impairment.

In fact, forty-eight patients had the condition.  None of the iridologists could reliably identify them beyond the level obtained by chance.  One of them thought that 88% had kidney disease and another believed that three quarters of them needed a kidney transplant.

The Journal of Optometry in 1981 carried details of an investigation in which an Australian iridologist was asked to identify thirty-three conditions in fifteen patients.  He failed to identify any of them but made sixty incorrect diagnoses.

In 2000, Professor Edzard Ernst published a comprehensive review in the Archives of Opthamology and showed that the iridologists were simply guessing.  Those few trials which claimed to show effectiveness of iridology had been designed with deliberate bias.  All of the trials of iridologists had demonstrated that it was not a form of diagnosis.

Why doesn't iridology work?
Despite the fact that some people believe the iris is a reflection of the state of the body, the evidence required to make that belief trustworthy is lacking.  A diagnosis requires that causes are reliably associated with outcomes,

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