Iridology (sometimes referred to as iris diagnosis) is based on the bizarre belief that each area of the body is represented by a corresponding area in the iris of the eye (the colored area around the pupil). According to this viewpoint, a person's state of health and disease can be diagnosed from the color, texture, and location of various pigment flecks in the eye. Iridology practitioners claim to diagnose "imbalances" that can be treated with vitamins, minerals, herbs, and similar products. Some also claim that the eye markings can reveal a complete history of past illnesses as well as previous treatment. One textbook, for example, states that a white triangle in the appropriate area indicates appendicitis, but a black speck indicates that the appendix had been removed by surgery. Iridology chartsâ€”dozens of which existâ€”vary somewhat in the location and interpretation of their iris signs. Some iridologists use a computer to help them analyze eye photographs and select the products they recommend. Sclerology is similar to iridology but interprets the shape and condition of blood vessels on the white portion (sclera) of the eyeball. 
This iridology chart was developed by a prominent naturopath more than 70 years ago. It relates various spots on the eye to about 50 parts of the body. The innermost blue circle in both eyes, for example, is said to reflect the health of the stomach. The topmost quadrants are said to represent the brain (cerebrum and cerebellum) and other parts of the head.
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.
Bernard Jensen, D.C. (1908-2001), the leading American iridologist, stated that "Nature has provided us with a miniature television screen showing the most remote portions of the body by way of nerve reflex responses." He also claimed that iridology analyses are more reliable and "offer much more information about the state of the body than do the examinations of Western medicine."
A British iridology organization states that there are three main "constitutional types" of iris color:
- The blue eyed constitution ("lymphatic type"), whose "inherent tendencies" include: "Re-activity of the lymphatic system (adenoid and tonsil irritations; splenitis; swollen lymph nodes; irritated appendix; catarrh with exudations; eczema; acne; flakey, dry skin; dandruff; asthma; coughs; bronchitis; sinusitis; diarrhoea; arthritis; vaginal discharge; eye irritations; fluid retention."
- The "pure brown eyed constitution ("haematogenic type"), whose "inherent tendencies" include: "Anaemia; lack of catalysts (iron, gold, arsenic, copper, zinc, iodine); blood diseases (hepatitis, Jaundice); muscle spasms; arthritis; chronic degenerative illness; endocrine disorders (thyroid, adrenals & pituitary); spleenic disturbances; poor lymphatic drainage; swollen glands; Hodgkin's Disease; flatulence; constipation; colonic tumour; dyspepsia; digestive disorders with lowered enzymatic production; frequent intolerance to cows milk; ulcers; liver, gall-bladder & pancreatic malfunctions; Diabetes; circulatory disorders; auto-intoxication."
- The combination of the two "mixed or biliary type"), whose "inherent tendencies" include: "Flatulance; constipation; colitis; hypoglycaemia; Diabetes; blood diseases; gall-stones; liver, gall-bladder, bile duct & pancreatic disorders; gastro-intestinal weakness with spasm; Haematogenic & Lymphatic Constitutional strengths & weaknesses." 
Russell S. Worrall, O.D., an assistant clinical professor of optometry at the School of Optometry, University of California, Berkeley, has noted that many of the conditions detected by practitioners of iridology are â€œdiseasesâ€ whose existence has been disputed or discredited by scientific investigation. Worrall also points out how spurious diagnoses by iridologists can have serious consequences, as illustrated by the case of an accountant who consulted a chiropractor who practiced iridology:
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! 
In 1979 Bernard Jensen and two other proponents failed a scientific test in which they examined photographs of the eyes of 143 persons in an attempt to determine which ones had kidney impairments. (Forty-eight had been diagnosed with a standard kidney function test, and the rest had normal function.) The three iridologists showed no statistically significant ability to detect which patients had kidney disease and which did not. One iridologist, for example, decided that 88% of the normal patients had kidney disease, while another judged that 74% of patients sick enough to need artificial kidney treatment were normal . Click here to see an example of Jensen's iridology chart.
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 .
In the late 1980s, five leading Dutch iridologists failed a similar test in which they were shown stereo color slides of the right iris of 78 people, half of whom had gallbladder disease. None of the five could distinguish between the patients with gallbladder disease and the people who were healthy. Nor did they agree with each other about which was which . These negative results, of course, are not surprising, because there is no known mechanism by which body organs can be represented or transmit their health status to specific locations in the iris.
In another study, researchers took color photographs of the eyes of 30 patients with ulcerative colitis, 25 with coronary heart disease, 30 with asthma, 30 with psoriasis, and a control group matched for age and gender. The photographs were coded and analyzed by an investigator, both manually and by a computer program according to criteria generated by leading iridologists. Using either method, discrimination between cases and controls was not different from what would be expected by chance. The authors concluded that "diagnosis of these diseases cannot be aided by an iridological-style analysis." 
In 1998, Eugene Emery, a science writer for the Providence Journal, tested the ability of two iridologists to assess his health and to match slide he had prepared of the eyes of eight people who had been medically diagnosed. Both iridologists scored very poorly .
In 2000, Dr. Edzard Ernst issued a thorough review of published reports up to that time. Noting that none of the "positive" studies had been properly designed, he concluded:
Might iridology be doing any harm? Waste of money and time are two obvious undesired effects. The possibility of false-positive diagnoses, ie, diagnosingâ€”and subsequently treatingâ€”conditions that did not exist in the first place, seems more serious. The real problem, however, might be false-negative diagnoses: someone may feel unwell, go to an iridologist, and be given a clean bill of health. Subsequently, this person could be found to have a serious disease. In such cases, valuable time for early treatment (and indeed lives) can be lost through the use of iridology .
A study published in 2005 tested whether iridology could be useful in diagnosing common forms of cancer. An experienced practitioner examined the eyes of 68 people who had proven cancers of the breast, ovary, uterus, prostate, or colorectum, and 42 for whom there was no medical evidence of cancer. The practitioner, who was unaware of their gender or medical details, was asked to suggest up to five diagnoses for each person and his results were then compared with each subject's known medical diagnosis. Iridology correctly diagnosed cancer in only 3 of the 68 cases .
Herbalist Michael Tierra has described how he became disillusioned with iridology. After making various observations, he stopped using it but still hoped that it would turn out to have some value. Then, however:
A younger colleague fully equipped with the most up-to-date specialized iridology equipment introduced himself and stated that he wanted to give iridology readings at my clinic and at the same time monitor the course of my patients over a period of six months.
Given the fact that for most of us as well my patients six months is quite a long period, there was ample opportunity for many of these to go through a variety of health-related changes. Some people became well and got sick again with either the same or perhaps a different set of symptoms, others suffered injuries or operations. They all had their irises repeatedly photographed and studied by my colleague and myself. Where was Peczely's owl or the markings he claimed to observe in patients of the 19th century Hungarian hospital ward? Where were the fine white healing lines that were supposed to knit together the small dark lacunae corresponding to the healing of operations and injuries of different parts of the body?
Our conclusion after six months: my colleague, trying to hold on to the fast disappearing shred of belief in the validity of iridology sheepishly and somewhat guiltily sold his camera to another would-be iridology enthusiast. I buried my official iridology magnifying head band in a box in a dark, hopefully soon forgotten area of my office closet, where I must confess it still remains after over 15 years, unopened .
Another former iridologist, Joshua David Mather Sr., has written a detailed account of the origin and termination of his beliefs. He began studying iridology at age nine when his father became a practitioner. He abandoned it at age 25 after examining polaroid films of many patients and finding out that although their symptoms often improved, their eye markings never changed .
The Bottom Line
Iridology makes no anatomic or physiologic sense. It is not merely worthless. Incorrect diagnoses can unnecessarily frighten people, cause them to waste money seeking medical care for nonexistent conditions, or steer them away from necessary medical care when a real problem is overlooked.
Some multilevel distributors are using iridology as a basis for recommending dietary supplements and/or herbs. Anyone who does this and is not a licensed health professional would be guilty of practicing medicine without a license, which is a violation of state law.
If you encounter anyone practicing iridology, please complain to your state attorney general.
- About iris constitutions. Guild of Naturopathic Iridologists International Web site, accessed August 20, 2004.
- Worrall RS. Iridology: Diagnosis or delusion? Skeptical Inquirer 7(3):23-35, 1983.
- Simon A and others. An evaluation of iridology. JAMA 242:1385-1387, 1979.
- Cockburn DM. A study of the validity of iris diagnosis. Australian Journal of Optometry. 64:154-157, 1981.
- Knipschild P. Looking for gall bladder disease in the patient's iris. British Medical Journal 297:1578-1581, 1988.
- Buchanan TJ and others. An investigation of the relationship between anatomical features in the iris and systematic disease with reference to iridology. Complementary Therapies in Medicine 4:98-102, 1996.
- Emery CE. [emery.html Iridology: Do the eyes have it]? Nutrition Forum 6:5-6, 1989.
- Ernst E. Iridology: Not useful and potentially harmful. Archives of Ophthalmology 118:120-121, 2000.
- MÃ¼nstedt K and others Can iridology detect susceptibility to cancer? A prospective case-controlled study. Journal of Alternative and Complementary Medicine 11;515-519, 2005.
- Tierra M. A comparative evaluation of diagnostic systems used in herbal medicine. Accessed Dec 23, 1998.
- Mather JD. [confessions.html Confessions of a former iridologist]. Quackwatch, Sept 10, 2004.