Iridology (also known as iridodiagnosis) is an alternative medicine technique whose proponents believe that patterns, colors, and other characteristics of the iris can be examined to determine information about a patient's systemic health. Practitioners match their observations to iris charts which divide the iris into zones which they correspond to specific parts of the human body. Iridologists see the eyes as "windows" into the body's state of health.
Iridologists use the corresponding charts to highlight certain systems and organs in the body as healthy and others as overactive, inflamed, or distressed. Iridologists believe this information may be used to demonstrate a patient's susceptibility towards certain illnesses, to reflect past medical problems, or to predict health problems which may be developing.
Iridology is not supposed to be used to diagnose. Instead it should be used as one of the methods to help assess the patient in order to come up with a more accurate diagnosis. As it is not a method of treatment, its practitioners often study other branches of alternative medicine, such as naturopathy.
Iridologists generally use equipment such as a flashlight and magnifying glass, cameras or slit-lamp microscopes to examine a patient's irises for tissue changes, as well as features such as specific pigment patterns and irregular stromal architecture. The markings and patterns are usually compared to an iris chart that correlates specific zones of the iris with specific parts of the body. Typical charts divide the iris into approximately 80-90 zones. For example, the zone corresponding to the kidney is in the lower part of the iris, just before 6 o'clock. Some iridology charts differ in their association between body parts and areas of the iris.
According to iridologists, details in the iris reflect changes in the tissues of the corresponding body organs. One well-known practitioner, Dr. Bernard Jensen, puts it this way: "Nerve fibers in the iris respond to changes in body tissues by manifesting a reflex physiology that corresponds to specific tissue changes and locations." This means that a bodily condition will translate to a noticeable change in the appearance of the iris. For example, acute inflammatory, chronic inflammatory and catarrhal signs may indicate involvement, maintenance, or healing of corresponding distant tissues, respectively. Other features that iridologists look for are contraction rings and Klumpenzellen, which may indicate various other health conditions, as interpreted in context.
The first explicit description of iridological principles such as homolaterality (without using the word iridology) are found in Chiromatica Medica, a famous work published in 1665 and reprinted in 1670 and 1691 by Philippus Meyeus (Philip Meyen von Coburg).
The first use of the word Augendiagnostik ("eye diagnosis," loosely translated as iridology) began with Ignaz von Peczely, a 19th-century Hungarian physician. The most common story is that he got the idea for this diagnostic tool after seeing similar streaks in the eyes of a man he was treating for a broken leg and the eyes of an owl whose leg von Peczely had broken many years before. At the First International Iridological Congress, Ignaz von Peczely's nephew, August von Peczely, dismissed this myth as apocryphal, and maintained that such claims were irreproducible.
The German contribution in the field of natural healing is due to a minister Pastor Felke, who developed a form of homeopathy for treating specific illnesses and described new iris signs in the early 1900s. However, Pastor Felke was subject to long and bitter litigation. The Felke Institute in Gerlingen, Germany was established as a leading center of iridological research and training.
Iridology became better known in the United States in the 1950s, when Bernard Jensen, an American chiropractor, began giving classes in his own method. This is in direct relationship with P. Johannes Thiel, Eduard Lahn (who became an American under the name of Edward Lane) and J Haskell Kritzer. Jensen insisted on the importance of the body's exposure to toxins, and the use of natural foods as detoxifiers.
Few medical researchers managed to secure funding to study the possible non-visual functions of the eye. In a paper published in Medical Hypotheses (Waniek, 1987), one group tried to explain the observed patterns of iris transparency that distribute light into the ora serrata (the edge of the optic retina) by postulating a functio ocularis systemica (systemic eye function). Based on this hypothesis, the researchers developed an experimental trans-iridal light therapy method; however, no other confirmation of the theory and method exists to date. Other results from this research include early attempts at computerized iris imaging for the purpose of iridologic diagnosis (Popescu et al., 1986) .
Criticism of iridology
The majority of medical doctors reject all the claims of all branches of iridology and label them as pseudoscience or even quackery. Iridologists are rarely physicians. Iridology can only be studied at private institutions, and it is not taught in conventional or naturopathic medical schools.
Critics, including most practitioners of mainstream medicine, dismiss iridology, largely because published studies have indicated a lack of success for its claims. The proposed correlation between illness in the body and coinciding observable changes in the iris is unsupported by clinical data. In controlled experiments , practitioners of iridology have performed statistically no better than chance in determining the presence of a disease or condition solely through observation of the iris. (See the scientific method page for details of how modern scientific theories are suggested and tested.)
It has been pointed out that the premise of iridology is at odds with the notion that the iris does not undergo changes in an individual's life. Iris texture is a phenotypical feature which develops during gestation and remains unchanged after birth. There is no evidence for changes in the iris pattern other than variations in pigmentation in the first year of life, eventual freckles and variations caused by glaucoma treatment. This stability of iris structures is at the foundation of iris recognition for identification purposes.
Scientific research into iridology
Well controlled scientific evaluation of iridology has shown entirely negative results, with all rigorous double blinded tests failing to find any statistical significance to its claims.
In a study published in the Journal of the American Medical Association (Simon et al., 1979), three iridologists incorrectly identified kidney disease in photographs of irises and often disagreed with each other. The researchers concluded: "iridology was neither selective nor specific, and the likelihood of correct detection was statistically no better than chance."
Another study was published in the British Medical Journal (Knipschild, 1988). Paul Knipschild MD, of the University of Limburg in Maastricht, selected 39 patients who were due to have their gall bladder removed the following day, because of suspected gallstones. He also selected a group of people who did not have diseased gall bladders to act as a control. A group of 5 iridologists examined a series of slides of both groups irises. The iridologists were not able to identify correctly which patients had gall bladder problems and which had healthy gall bladders. For example one of iridologists diagnosed 49% of the patients with gall stones as having them and 51% as not having them. He diagnosed 51% of the control group as having gall bladder problems and 49% as not. Dr Knipschild concluded: "this study showed that iridology is not a useful diagnostic aid." Iridologists defended themselves with the same considerations as above, but also attacked the methodology of the study.
Ernst, 2000, said: "Does iridology work? [...] This search strategy resulted in 77 publications on the subject of iridology. [...] All of the uncontrolled studies and several of the unmasked experiments suggested that iridology was a valid diagnostic tool. Such investigations are wide open to bias. The discussion that follows refers to the 4 controlled, masked evaluations of the diagnostic validity of iridology. [...] In conclusion, few controlled studies with masked evaluation of diagnostic validity have been published. None have found any benefit from iridology. As iridology has the potential for causing personal and economic harm, patients and therapists should be discouraged from using it."
Regulation, licensure, and certification
In Canada and the United States, iridology is not regulated or licensed by any governmental agency. Numerous organizations offer certification courses.
- Cline D; Hofstetter HW; Griffin JR. Dictionary of Visual Science. 4th ed. Butterworth-Heinemann, Boston 1997. ISBN 0-7506-9895-0
- Jensen B; "Iridology Simplified". 2nd ed., Escondido 1980.
- Waniek, D.A., Medical Hypotheses 1987;23(1): 309-312. PMID 3614020
- Popescu, M.P.; Waniek D.A., Rev Chir Oncol Radiol O R L Oftalmol Stomatol Ser Oftalmol 1986;30(1): 29-33. PMID 2940632 (in Romanian)
- Ernst E. Iridology: not useful and potentially harmful. Arch. Ophthalmol. 2000 Jan;118(1):120-1. PMID 0636425
- Inside Iris Recognition
- Iris Recognition
- Simon A., Worthen D.M., Mitas JA 2nd. An evaluation of iridology. JAMA. 1979 Sep 8;242(13):1385-9. PMID 480560
- Knipschild P. Looking for gall bladder disease in the patient's iris. BMJ. 1988 Dec 17;297(6663):1578-81. PMID 3147081
- Western Medicine looks at Iridology ... by Bill Caradonna R.Ph. (Several more rebuttals of official critics of iridology are found at the same resource online.)
- Is the Iris a Receptor? by Vincenzo Di Spazio (2000)
- Iridology by Dr Lisa Niebergall
- Celestial Healing site about iridology (source of the iris charts used in this article)
- Canadian Journal of the Science and Practice of Iridology (a good resource, no longer available as hard print)
- Canadian Neuro-Optic Research Institute (Canada)
- The Israeli center for Advanced Multidimensional Iridology. (Israel)
- firstname.lastname@example.org - Iridology saved my life
- The Skeptics Dictionary
- Iridology (small PDF file duplicating Knipschild and Simon data, with no independent additions, but with valuable illustrations)