Let's Take a Look at Iridology
By Don Bennett, DAS

Iridology is based on the contention that each area of the body, even specific organs, is represented by a corresponding area in the iris of the eye (the colored area around the pupil). It's claimed that while iridology cannot detect a specific disease, it can tell an individual if they have over or under activity in specific areas of the body. For example, an under-active pancreas might indicate a diabetic condition. But there are iridologists who will offer a diagnosis based on what they are seeing.

The idea that one part of the body maps to the rest of the body, including the organ systems, is a popular one among some alternative health practitioners. But when determining the legitimacy of something, we should consider the best scientific evidence... it should be subject to the scientific method, which was developed to protect researchers from their own subconscious biases, and from very convincing fraudsters.

As with reflexology (areas on the feet corresponding to various organs), or "toothology"...

...or "acneology"...

...or "lingualology"...

...there is no physical evidence of any anatomical, physiological, or neurological mechanism involving the eye that would allow for the ability that iridology says exists. Yes, if there's an excess of the pigment bilirubin caused by obstruction of the bile duct, you will certainly see this in the whites of the eyes (jaundice), and if someone is in ill health, an observant person can sometimes see this general state of ill health represented in the iris of the eyes if they know what they're looking at, but as to indications of specific issues with specific organs, there has not been any corroborating evidence of this... no credible research demonstrates direct connections between specific iris sectors and individual organs as depicted in iridology maps.

And think about it, what evolutionary pressure would have led to such a mechanism? Evolutionary biologists offer no plausible explanation for one. However, behavioral psychologists do have an explanation for why these practices develop. They are often based on misunderstood observations that lead to hypotheses that become practices based on erroneous conclusions, and the notion that "it sounds like it makes sense to me" is not part of a rigorous scientific thought process.

When science tried to substantiate the claims of iridology, five experienced iridology practitioners from around the U.S. were invited to participate in a study. All expenses paid. Four agreed. One was not available regardless of when the testing could occur. And when tested, these four professional iridologists did no better than a coin toss in being able to discern issues with the test subjects' organs. Actually it was worse than that; iridology identified the correct conditions in only 3 cases out of the 140 test subjects. In other studies that focused on cancer specifically, iridology was of "no value" in determining the cancer patients from healthy individuals.

So, under controlled conditions iridologists could not distinguish the healthy subjects from the very ill. And no, the researchers weren't biased against them; they weren't minions of the medical industry. So they weren't "out to get them"; they honestly wanted to see if there was any truth to the claims of efficacy. And there wasn't. But this doesn't stop some people from honestly believing that it is a real thing, and human nature is responsible for this tendency, which is why the scientific method was created.

The ability to simply look in your eyes and see a problem with an organ sounds too good to be true. And if it were true, it would be a fantastic diagnostic tool. But often, if it sounds too good to be true, it likely isn't. As with many things in the health care industry, Let the Buyer Beware applies here too. But hey, if an iridology session gets you to clean up your diet and adopt other healthful lifestyle practices, that's a good thing, even though not dealing with reality isn't.

Bottom line: From an unbiased scientific standpoint – focusing solely on biological mechanisms, controlled blinded studies, systematic reviews, and reproducibility – iridology does not work as a diagnostic tool. Its claims do not withstand empirical scrutiny. And based on this, it can be said that those practitioners who say its real are demonstrating that they are not good researchers who emply the ethos of science.