While its origins are lost in antiquity, like chiropractic, acupuncture and homoeopathic medicine, it has undergone a resurgence in recent years. Its modern development is attributed to Dr Ignatz von Peczely of Hungary, who, after observing a black spot which appeared in the iris of an owl that had been injured, published a treatise in 1866, theorizing an iris-body connection.

Briefly stated, the hypothesis posits that illness or disease alters the topography of the iris through the neuro-optic reflex – that is, as the organs of the body are connected by nerves to the brain and the iris is likewise connected, there is a relationship between changes in bodily functions and the coloured diaphragm (iris) surrounding the black pupillary opening in the centre.

A latter day proponent of iridology is Bernhard Jensen, whose charts in particular have gained a reputation and are those most commonly used to show a correlation between iris representation and the body's organs. Using this method, one iridologist tested by A. Simon et al. (An Evaluation of Iridology, 1979), correctly diagnosed eighty-five per cent of patients with renal disease. There is a divergence of opinion on interpretation by some diagnosticians however. Jensen, for example, denies the ability to diagnose death, whereas Kriege in his Fundamental Basis of Iris Diagnosis, gives three signs of imminent death.

J. Piesse, (1980), in the Australian Physician states that cancer cannot be diagnosed, but Kriege and Jensen do not agree, Jensen presenting a number of cases of breast, bowel and lung cancers diagnosed through iris manifestations.

Despite this divergence of opinion, iris diagnosis is popular with those whom, for one reason or another, are disillusioned with orthodox medical procedures and seek the advice of alternative medicine practitioners.

Iridology, like Sclerology (the study of the red lines in the whites of the eyes), dermaglyphics (the lines on the bottom of the feet), phrenology (diagnosis using the bumps on the head) and acupuncture, all teach that because all parts of the body are connected by nerves to the brain, the state of one part is reflected in another. No evidence is ever offered to support the contention and it is analogous to saying, that because all telephones are connected to a central telephone exchange one automatically reacts with another.

Iridologists try to give iris diagnosis some semblance of respectability by drawing as an analogy the diagnosis of systemic disease by ophthalmoscopy, overlooking the pathological fact that the retinal structures are directly affected by specific diseases whereas the iris is not.

The discrediting of iris topography begins with the lack of conformity and the anomalies and discrepancies appearing in the diagnostic charts available. Jensen's chart, for example, shows the heart to be represented only in the left eye. Kriege however, finds the "right heart" represented in the right iris, while the "left heart" appears in the left iris. Kriege also claims that his adherents can diagnose from a photograph without even seeing the patient. These claims were put to the test by D.M. Cockburn (1981), at the University of Melbourne, where iridologists were invited to evaluate before-and-after photographs of patients who had developed an acute disease. The only set of photographs in which they perceived a change were those of a control subject taken two minutes apart.

Further evidence of the diagrammatical inefficacy of iris charts was reported by Jancke in 1955 (cited by Hoebens 1983). Using the charts developed by leading iridologists Vida and Deck, Jancke examined the medical records of 150 patients and then compared them with the iridological diagnoses, several "hits" were established. The chart was then turned 90 degrees in such a way that the part of the iris associated with one part of the body was now represented by another. The number of hits was found to be the same as when the chart was held in its iridologically proper position!

The iridologist who correctly diagnosed eighty-five per cent of the patients who had renal disease, also diagnosed eighty five per cent of the healthy patients as also having renal disease! Studies spanning several decades and involving hundreds of patients are even more revealing. In 1911-7, Frese (cited by Hoebens 1983) examined 762 patients whose conditions were known, looking for the appropriate "markings" in the irises. The results were disastrous for the iridological claims. The irises revealed diseases from which the patients were not suffering and failed to reveal actual illnesses.

Another carried out in the Netherlands (Knipschild 1988), sought to determine the ability of five "leading" indologists to observe the presence of inflamed gall bladder disease in thirty-nine patients vs thirty-nine controls of the same sex and age. Stereo colour slides were presented of the right eye and presented in random order. The iridologists were unable to perform any better than chance in their ability to recognize those diseases and exhibited an inter performer agreement consistency of sixty per cent which is only slightly higher than chance (a test of reliability).

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