MD, PhD, FMedSci, FRSB, FRCP, FRCPEd

Ignaz von Peczely (1826-1911), a Hungarian physician, got the idea for iridology (or iris-diagnosis) more than a century ago, after seeing streaks in the iris of a man he was treating for a broken leg, and similar phenomena the iris of an owl whose leg von Peczely had broken many years before. He subsequently became convinced that his method was able to distinguish between healthy organs and those that are overactive, inflamed, or distressed. Iridology became internationally known when US chiropractors began adopting this method in their clinical practice. In the United States, most insurance programs do not cover iridology but, in some European countries, they often do. In Germany, for instance, 80% of the Heilpraktiker (non-medically qualified health practitioners) practice iridology.

Iridologists claim to be able to diagnose the health status of an individual, medical conditions or predispositions to disease through abnormalities of pigmentation in the iris. The popularity of iridology renders it necessary to ask whether this method is valid.

The aim of my systematically review from 1999 was to critically evaluate all available, reliable tests of iridology as a diagnostic tool. Four case control studies were included; these are investigations where iridologists are asked to tell by looking at the iris of individuals whether that person does or does not have a certain condition. The majority of these studies suggested that iridology is not a valid diagnostic method. Back then, I concluded that “the validity of iridology as a diagnostic tool is not supported by scientific evaluations. Patients and therapists should be discouraged from using this method.”

Since the publication of my article, several further studies have emerged:

One German team conducted a study investigating the applicability of iridology as a screening method for colorectal cancer. Digital color slides were obtained from both eyes of 29 patients with histologically diagnosed colorectal cancer and from 29 age- and gender-matched healthy control subjects. The slides were presented in random order to acknowledged iridologists without knowledge of the number of patients in the two categories. The iridologists correctly detected 51.7% and 53.4%, respectively, of the patients’ slides; therefore, the likelihood was statistically no better than chance. Sensitivity was, respectively, 58.6% and 55.2%, and specificity was 44.8% and 51.7%. The authors’ conclusion was blunt: “Iridology had no validity as a diagnostic tool for detecting colorectal cancer in this study.”

A study from South Africa aimed to determine the efficacy of iridology in the identification of moderate to profound sensorineural hearing loss in adolescents. A controlled trial was conducted with an iridologist, blind to the actual hearing status of participants, analysing the irises of participants with and without hearing loss. Fifty hearing impaired and fifty normal hearing subjects, between the ages of 15 and 19 years, controlled for gender, participated in the study. An experienced iridologist analysed the randomised set of participants’ irises. A 70% correct identification of hearing status was obtained with a false negative rate of 41% compared to a 19% false positive rate. The respective sensitivity and specificity rates therefore were 59% and 81%. The authors of this investigation concluded that “iridological analysis of hearing status indicated a statistically significant relationship to actual hearing status (P < 0.05). Although statistically significant sensitivity and specificity rates for identifying hearing loss by iridology were not comparable to those of traditional audiological screening procedures.”

A further German study investigated the value of iridology as a diagnostic tool in detecting some common cancers. One hundred ten subjects were enrolled; 68 subjects had histologically proven cancers of the breast, ovary, uterus, prostate, or colorectum, and 42 were cancer-free controls. All subjects were examined by an experienced practitioner of iridology, who was unaware of their medical details. He was allowed to suggest up to five diagnoses for each subject and his results were then compared with each subject’s medical diagnosis to determine the accuracy of iridology in detecting malignancy. Iridology identified the correct diagnosis in only 3 cases (sensitivity, 0.04). The authors concluded that “iridology was of no value in diagnosing the cancers investigated in this study.”

Based on these results it is impossible, I think, to claim that iridology is a valid or useful diagnostic tool. As there is no anatomical or physiological basis for its assumptions, iridology is not biologically plausible. Furthermore, the available clinical evidence does not support its validity as a diagnostic tool. In other words, iridology is bogus. This statement is in sharp contract to the information consumers receive about the method on uncounted websites, books, articles, etc. One website picked at random provides the following information:

The iris reveals changing conditions of every part and organ of the body. Every organ and part of the body is represented in the iris in a well defined area. In addition, through various marks, signs, and discoloration in the iris, nature reveals inherited weaknesses and strengths.

By means of this art / science, an iridologist (one who studies the coloration and fiber structure of the eye) can tell an individual his/her inherited and acquired tendencies towards health and disease, his current condition in general, and the state of every organ in particular.

Iridology cannot detect a specific disease, but, 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.

Another source claims:

The underlying platform of iridology is that that eyes act as a ‘window’ to a person’s health & well being. This ‘window’ enables the practitioner to see whether areas or organs within the body are healthy, inflamed or ‘over active’. It also enables them to assess a person’s past/ possible future health problems & consider if the patient has a susceptibility to certain diseases. It is important to understand that iridology is simply a method of diagnosis & analysis.

You may well think that none of this really matters. Who cares whether iridology is bogus or not! I would argue that it does matter. Bogus methods cost money that could be better spent elsewhere. More importantly, false positive and false negative diagnoses generated by bogus diagnostic methods can put lives at risk.

But there is a more general and perhaps more crucial point here: alternative medicine is an area where people far too easily get away with ignoring the published evidence and scientific consensus. In the last two decades, I have seen many alternative modalities getting scientifically dis-proven; not in a single such instance can I remember that the corresponding alternative practitioners and their professional organisations took any notice of this fact, and not once did I notice that their practice had changed.

If research is  systematically ignored, it becomes a useless appendix. More importantly, progress is then stifled to the detriment of all our best interests.

14 Responses to Iridology: if evidence is systematically ignored, lives are put at risk

  • I wonder if the people who believe in iridology use airport iris recognition systems? You know, the ones based on the fact that the iris doesn’t change?

  • I just have to say doctor you’ve spent a lot of time coming to the wrong conclusions about something you know absolutely nothing about.
    I have studied Iridology and find that it’s fascinating and in all the cases I’ve looked at; extremely accurate.
    I can attest to the fact that I’ve never harmed ANYONE with my study of their eyes while you doctor have probably done more harm to your patients in a lifetime than any one layperson could do in several.
    I just wish once the medical community would quit relying on what you would call “bogus” organizations like the FDA that don’t even study the poisons you put into people all the while making a very good living.

    Please refrain from pointing fingers at something you haven’t actually STUDIED it then YOU are the one that’s incorrect.
    Do your own homework on it….or even go to an Iridologist and see what you can…..it will change your life…and might even save it…..that is if you’re not as closed minded as I suspect you are.
    Good day.

    • “extremely accurate”
      ???????????????????
      any evidence?

    • Kimberly Weninger

      Where would you like me to start?

      Your failure to understand science?

      Your failure to understand evidence?

      Your failure to understand biology and human anatomy?

      Your failure to understand cognitive biases?

      Your failure to think critically?

      You choose.

  • I can tell that if you have a major health problem you eye will not be recognized by a iris recognition systems, you can google it… but the iris patter check points of coincidence and have some grade of error… and there are tons of pictures of people sick and the eye and wen they cure how the eye change…. so fuck evidence and just call it bogus…

  • @Weninger & antonio

    I went through this some years ago and studied everything there is to find about this. Both Iridology and Sclerology and other related genres are, in contrast to most other “alternative” health-related practices rather easy to disprove. In the first place, these methods have no prior plausibility as there are no anatomical or physiological circumstances, which might explain how you can diagnose health-conditions by these means. A score of studies have been performed, which totally fail to show any efficacy of iridology/sclerology. I do not want to spend my time finding the references, they are easily obtained with basic skills in google-ing. Several tests have shown that iridologists or sclerologists are no better than monkeys at diagnosing ailments, which they commonly pretend to discern.

    I had the privilege recently of reading through a book on “eyeology” by one of the purported “masters” of that trade, one Leonard Mehlmauer. The only thing I learned from reading his works was that he has no understanding of the human body or its functions. He knows some names and phrases, the rest is baloney. I will refrain from using the word most fitting for describing his qualities but if you know the works of Dostoyevsky you will understand what term I am alluding to.
    Eyeology (iridology and sclerology) are disproven nonsense. Its a simple and unusually well established fact.

  • In the mid-70’s the AMA raided a lot of iridologist, some who were medical doctors,who were using iridology in their practice. Many did prison time for allegedly “practicing medicine without a licence.” I’ve seen the efficacy of iridology in a clinical research setting first hand, so I’m not convinced that the claim that iridology is bogus . To me these statements are just a more sophisticated way of discrediting iridology. Iridology has, in the past, threatened the livelihood of western medical practitioner.

  • Hmm, the heartbeat’s pulse wave form has been proven to be correlated with various diseases.
    See the work of Jingjing Xia, and Simon Liao

    As I think of this issue, it makes for a good big data, machine learning, data science project.

    Get thousands of medical charts with confirmed diagnosis of different diseases.
    Also get pictures of the eyes.

    Analyze the data. Apply algorithms and machine learning.
    What results do you get?

    • ” heartbeat’s pulse wave form has been proven to be correlated with various diseases”
      links to evidence please

    • Rather strange coincidence that I sort of happened upon your comment while doing an unrelated search for the lack of efficacy of Iridology. Only a few hours earlier I was looking through the academic calendar for the applied computer science program at the University of Winnipeg where Simon Liao teaches. Had the opportunity to meet him a few years ago. Pretty funny guy doing some fascinating research.

      With regard to the rest of your comment, as a software dev I’d also be interested in applying machine learning to a large labeled dataset of this sort. Not specifically for Iridology purposes because I think it’s a waste of resources, but more for generally applicable medical research. I believe something along these lines is currently being studied at the University of British Columbia and a few in the states.

  • Having written a critical essay about iridology in my language, I was countered with a long, mostly translated rant containing a cavalcade of all the classical fallacies, mostly ‘ad hominem’ towards the “specialists” and Steven Barrett in particular.
    Anyway, one little claim caught my eye and I tried in vain to locate its origins.
    This claim seems to pervade many defensive writings on iridology and goes like this:

    WHAT IS THE ACCURACY OF IRIS ANALYSIS?

    The accuracy and reliability of iris signs as reflex indications of tissue pathology in the body have been confirmed in many thousands of instances by: laboratory tests, X-rays, and other commonly accepted diagnostic approaches. Recent research from clinical trials in South Korea from Aju University have shown that the validity of using iridology for predicting diseases ranges between 71.4% and 100% accuracy.

    The accepted clinical results by the Korean Government include:

    Diseases of: % Accuracy

    ___________________________

    Digestive system 90.2%

    Endocrine system 86.4%

    Muscle/Skeletal system 72.2%

    Nervous system 79.9%

    Urogenital system 85.7%

    Cardiovascular system 75%

    Circulatory system 81.6%

    Immune system 54.2%

    I have hitherto been unsuccessful in finding the source of this. One iridology site gives two links, Neither of them are useful. https://herenowhealing.com/truth-beauty/files/category-iridology.html (In the third chapter 🙂 ) This is only one of many sites that echo claims of Korean research confirming this, without citing any source.

    Anyone here have an idea or better search-skills than I have? Where in the world does this story of Korean government-sanctioned proof of iridology’s positive predictive value come from? I would love to be able to include a proper analysis of it in a little article.

Leave a Reply

Your email address will not be published. Required fields are marked *

Gravityscan Badge

Recent Comments

Note that comments can be edited for up to five minutes after they are first submitted.


Click here for a comprehensive list of recent comments.

Categories