Iridology: More Woo for Profit!


SDHoS would like to thank Austin James for bringing this to our attention.

Iridology (also known as iridodiagnosis or iridiagnosis) is an alternative medicine technique whose proponents claim that patterns, colors, and other characteristics of the iris can be examined to determine information about a patient’s systemic health.


Proponents of iridology attribute its development to Ignatz von Peczely, a Hungarian physician who, during his childhood, had accidentally broken the leg of an owl and noticed a black stripe in the lower part of the owl’s eye. Nonadherents suggest that von Peczely may have developed his theory to pass time while he was imprisoned after the 1848 Hungarian revolution. After his release from prison he allegedly saved the life of his mother with homeopathic remedies, recalled the incident of the owl’s eye, and began studying the eyes of his patients.

Dangers of Iridology

Russell S. Worrall, O.D., an assistant clinical professor of optometry at the School of Optometry, University of California, Berkeley, points out how diagnoses by iridologists can have serious consequences, as illustrated by the case of an accountant who consulted a chiropractor who practiced iridology:[1]

During the course of treatment an iridology workup was recommended. The results indicated, among many other health problems, the presence of cancer. Overwhelmed, the patient spent the day in torment. Unable to consult his family physician . . . he finally sought my advice. After a lengthy discussion, I was able to allay his fears. . . . He wondered how an intelligent person such as himself could be caught up in such a deep emotional web over such a diagnosis. The story fortunately had a pleasant ending. However, the outcome could have been much more serious since the patient is also suffering from a heart condition, which was not noted on the iridology evaluation![2]

Is It Science? Alas, No.

In 1980, an experienced Australian iridologist underwent two tests. In the first, he examined photographs of 15 patients who had been medically evaluated and had a total of 33 health problems. The iridologist did not correctly diagnose any of these problems. In three cases he named a part of the body that had had trouble (for example, he said “lesion in throat area” for a patient whose tonsils had been removed during childhood), but he completely missed the other 30 problem areas and made 60 incorrect diagnoses. In the second trial, four people had their eyes photographed when they were in good health and rephotographed when they reported being ill. The iridologist made a large number of (incorrect) diagnoses from the initial photographs and was unable to accurately identify any organ that underwent a change when the health problem arose. He was also asked to compare iris photographs of another healthy individual taken only two minutes apart. He made five incorrect diagnoses for the first of these and four different incorrect ones for the second [3].

An excerpt from ‘Iridology’, By Dr. John Ankerberg and Dr. John Weldon[4]:

As reported in the Journal of the American Medical Association, scientific researchers at University of California San Diego tested three iridologists  and three ophthalmologists by having them study the iris photo­graphs of 143 subjects, 48 of whom had overt kidney failure. Two of the three iridologists had been “using the technique as their primary method of analysis of patients for more than forty years.” But the iridologists failed miserably. The number of false positives (healthy people diagnosed as having disease) and false negatives (diseased people diagnosed as healthy) was frightening. In fact, the iridologists’ accuracy was found to be worse than what one would expect with chance guessing. In other words, the iridologists would have been more accurate by picking their answers out of a hat than by deriv­ing them from an examination of the iris. Thus,

…the 2.5 percent level of renal disease diagnostic accuracy with iridology— only 11 of 20 patients with disease are correctly identified, while 421 normal people are identified as having disease—does not warrant reliance on this technique in the detection of renal disease…. There is a serious potential psychological harm to the subject of carrying the burden of detected “disease.” Of greater interest to physicians is the false-negative analysis. One of the observers (an iridologist), who employs the technique and draws conclusions based on it, correctly identified only 26 percent of the patients undergoing dialysis as having kidney disease. Physicians are well aware of the harm that can be done to these patients if they were to rely on iridology and thereby go without proper treatment.

There are many more failed tests of this pseudoscientific woo, but you get the idea.

Our Conclusions

Iridology as not science, and it is not medicine. It is quackery in the highest degree. It represents a clear danger to patients who may have serious medical conditions.

It’s also a danger to the financial well-being of those suffering no illness who may be sold various ‘woo’ treatments, as most iridologists also subscribe to other areas of alternative medicine. Our long-time readers probably remember from previous posts that alternative medicine doesn’t work. If it did, it would be called ‘medicine’, without the ‘alternative’ prepended.

For further reading on the subject, we recommend that you read ‘Confessions of a Former Iridologist‘ by Joshua David Mather Sr.  It’s a long read, but it describes how an honest, true believer in iridology and alternative medicine came to first doubt, and finally reject the pseudoscience.

We at SDHoS would like to encourage all our readers to seek actual, science-based medical attention when needed instead of nonscientific ‘woo’. As we’ve stated before, we like you and would prefer that you lead long, healthy lives.



[1] ‘Iridology is Nonsense’: Stephen Barrett, M.D.

[2] Worrall RS. Iridology: Diagnosis or delusion? Skeptical Inquirer 7(3):23-35, 1983

[3] Simon A and others. An evaluation of iridology. JAMA 242:1385-1387, 1979

[4] Iridology – Part 3: Dr. John Ankerberg and Dr. John Weldon

4 comments on “Iridology: More Woo for Profit!

  1. This guy appears only to exist on the internet as a professional debunker which makes me sceptical.Where are his credentials, his website off example?

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