Iridologists claim they can determine whether an organ is diseased by examining the iris, as opposed to the more logical tactic of looking at the organ.

The field has its roots in 19^th Century Hungary, where teenager Ignatz von Peczely accidentally broke an owl’s leg. Despite the animal’s shrieks and convulsing, von Peczely was able to detect a black stripe toward the bottom of his iris. Twenty years later, the now-Dr. von Peczely noticed a similar stripe in the same area when mending a patient’s broken leg.

Von Peczely went to work documenting other alleged eye markings in future patients. This, combined with post hoc reasoning and apopehnia, led to the first iridology chart. There are now many such charts and each has different diagnoses and treatments. Even what qualifies as a marking is subjective.

If a physician diagnosed a patient with tonsillitis, another doctor giving a second opinion would not instead determine it was appendicitis. Yet two iridologists might recommend a tonsillectomy and an appendectomy, respectively, because the field is driven by conflicting iridology maps and creative interpretations of eye specks and pigments.

I can’t blame the von Peczely for trying a different approach. But there’s no reason to use it today. Iridology has failed miserably in controlled scientific studies and there is no known mechanism by which body organs can transmit a health status via the iris.

Besides, the iris is one of the most static areas of the body. Biometric identification uses it as the identifying feature because its pattern is established in utero and is unchanging from then on, except for slight color change in newborns. Subsequent changes can only happen because of eye injuries or an eye disease such as glaucoma. And a person would know they had these conditions without having to consult an iridologist.

There have been at least a dozen attempts to put iridology to a scientific test and it has failed spectacularly each time.

In 1979, three iridologists were shown photos of 143 persons and asked to identify which ones had kidney trouble. One deduced that 88 percent of the healthy patients had kidney disease, while another determined that 74 percent of those with ailing kidneys were healthy. The third performed no better than chance.

The next year, an Australian iridologist examined photographs of 15 patients who had a total of 33 health problems. He struck out each time, failing to diagnose any of the diseases.

In the late 1980s, five Dutch iridologists were shown slides that included 78 persons with gallbladder disease. None of the five could distinguish between the patients with gallbladder disease and those without.

In another test, an experienced practitioner was asked to diagnose 68 patients. He correctly identified three of the patients as having cancer, which is much less impressive when one learns that all 68 had the disease.

These overwhelming failures are explained away with some Great Moments in Ad Hoc Reasoning. Specifically, it is sometimes asserted that iridologists are so medically savvy they are able to diagnose conditions years before they manifest. Or iridology may be touted as a way to determine how susceptible a patient may be to a particular disease. Of course, a decent physician could do that by considering a patient’s habits, diet, genetics, and family history. Some iridologists have taken to downplaying actual diseases and instead detect imaginary disorders such as electrostatic interference, magnetic imbalance, chronic stress, or toxin buildup. Still others use it as a pretext to sell herbal supplements and vitamins.

With most alternative medicines, the biggest danger is that of a patient being inadequately treated, such as battling high blood pressure with raspberry smoothies. That could still happen with this field since a patient might falsely be given clean bill of health. But the most likely danger with iridology is that a patient will be diagnosed for something he or she doesn’t have, leading to freaking out and pumping unnecessary medicine into themselves.

The only health issues the iris reveals are problems with the iris. If needing to have someone look deeply into your eyes, schedule a romantic dinner.