SPECIAL ARTICLE Iridology Not Useful and Potentially Harmful E. Ernst, MD, PhD, FRCP (Edin) ore than 1000 licensed naturopathic physicians practice in the United States,1 and iri- dology is being described as “the most valuable diagnostic tool of the naturopath.”2 Some therapists are using iridology as a basis for recommending dietary supplements and/or herbs.3 Several US iridologist organizations exist: the National Iridology Re- Msearch Association is an iridologists’ service organization, the International Association of Iridologists is the leading organization for European-style iridology and runs training programs (minimum of 72 hours in class), and the Bastyr Naturopathic College in Seattle, Wash, has an elective course on irid- ology (J. Colton, e-mail communication, December 2, 1998). In the United States, insurance pro- grams do not normally cover iridology, but in some European countries, they do. In Germany, for instance, 80% of the Heilpraktiker (nonmedically qualified health practitioners) practice iridology.4 Ophthalmologists may therefore ask what is iridology and how valuable is it? Arch Ophthalmol. 2000;118:120-121 Iridology, developed more than 100 years rial. Finally, my own files were searched. All ago, is the diagnosis of medical conditions bibliographies of articles thus obtained were through noting irregularities of the pigmen- scanned for further relevant publications. tation in the iris. Iridology assumes that all This search strategy resulted in 77 publi- bodily organs are represented on the sur- cations on the subject of iridology. Copies face of the iris via intricate neural connec- of all of these articles were obtained unless tions5 and that dysfunction of most organs it was clear from the title that it did not per- is marked on the iris, usually as a pigmen- tain to an experimental study. Those pub- tary change; the right half of the body is rep- lished in English, German, French, Span- resented in the right iris, the left half in the ish, and Italian were read in full. Of those left iris. Iridologists refer to maps of the iris published in other languages, the English on which each iris is divided into 60 sec- abstracts were read, and if they suggested a tors (much like the face of a clock), and each relevant investigation, translations of the full segment is related to an inner organ or article were obtained. bodily function. Heart diseases, for in- Most of the 77 papers were review ar- stance, are thus identified in the left iris ticles, comments, and descriptions of the somewhere between the 2- and 3-o’clock po- technique.6,7 Seventeen articles were classi- sitions. Iridologists study the iris in situ or fied as attempts to evaluate the diagnostic they produce high-quality color photo- validity of iridology. Most of these investi- graphs of both irides. gations were conducted without a control Does iridology work? To answer this group, and some (with or without a control question, the following databases were group) were not evaluator masked.8,9 All of searched: MEDLINE, EMBASE, and the uncontrolled studies and several of the CISCOM (all from their inception to the end unmasked experiments suggested that iri- of 1998). In addition, other experts on dology was a valid diagnostic tool. Such in- complementary or alternative medicine vestigations are wide open to bias. The dis- were asked for further references, and cussionthatfollowsreferstothe4controlled, professional societies of iridologists were masked evaluations of the diagnostic valid- addressed and invited to contribute mate- ity of iridology.10-13 Simon et al10 studied patients suffering From the Department of Complementary Medicine, School of Postgraduate Medicine from kidney disease as defined by a creati- and Health Sciences, University of Exeter, Exeter, England. nine level higher than 106 µmol/L (1.2 ARCH OPHTHALMOL / VOL 118, JAN 2000 WWW.ARCHOPHTHALMOL.COM 120 ©2000 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 09/30/2021 mg/dL); the controls were free of kid- controls was not different from that able time for early treatment (and in- ney disease. Patients were assessed as expected by chance. The authors deed lives) can be lost through the a total group as well as 2 separate sub- concluded that “diagnosis of these use of iridology. No data are avail- groups, one with moderately high cre- diseases cannot be aided by an iri- able on how frequently such prob- atinine levels (up to 433 µmol/L [4.9 dological-style analysis.”12 lems occur. Thus no firm judg- mg/dL]) and one with markedly high Cockburn13 published the re- ments are possible as to the damage creatinine levels (557-1414 µmol/L sults of 1 uncontrolled and 1 small done by iridology in real life. [6.3-16.0mg/dL]).Kidneydiseasewas controlled and evaluator-masked In conclusion, few controlled chosen for convenience and because trial in a single article. In the latter studies with masked evaluation of di- iridologistsfeltcomfortablewithit(and study, photographs were taken of 3 agnostic validity have been pub- with the study outline). Photographs patients (1 with pleurisy, 1 with gas- lished. None have found any ben- were taken of both irides of all 146 troenteritis, and 1 with an upper res- efit from iridology. As iridology has study participants, coded, and shown piratory tract infection), both in a the potential for causing personal to3experiencediridologistsand3oph- healthy and an acutely diseased state. and economic harm, patients and thalmologists. They were asked to cat- These were examined by the therapists should be discouraged egorize the photographs according to (masked) author of the article, who from using it. patients (kidney disease) and controls (no kidney disease). The resulting fre- was unable to detect changes in the pre- disease and during-disease photo- Accepted for publication June 30, 1999. quency of false-positive and false- Corresponding author: E. Ernst, negativediagnoseswasnotsignificantly graphs, other than slight artifactual varia- tions attributable to exposure variations MD, PhD, FRCP (Edin), Department differentfromthatexpectedbychance. in the printing and the positioning of re- of Complementary Medicine, School Simon and coauthors concluded that flections.13 of Postgraduate Medicine and Health “none of the 6 observers in this study Sciences, University of Exeter, 25 Vic- derived data of clinical importance or Even though this trial is burdened by 10 toria Park Rd, Exeter EX2 4NT, En- significance.” a minute sample size, the author con- gland (e-mail: [email protected]). Knipschild11 conducted an- cludes that iridology “does not ap- other investigator-masked case- pear to have any validity in the con- control study. His 39 patients had in- text of conventional medicine.”13 REFERENCES flamed gallbladder disease as Collectively,thesecontrolledand confirmed by subsequent surgery. masked studies do not support the no- 1. Berman BM, Larson DB. Alternative Medicine: Ex- Patients with jaundice were ex- tion that iridology is a valid diagnos- panding Medical Horizons, A Report to the Na- tional Institutes of Health on Alternative Medical cluded. Controls were matched for tic tool. There is little reason to suspect Systems and Practices in the United States. age and sex and had no signs or that a type II error rendered these in- Bethesda, Md: US Dept of Health and Human Ser- vices, Public Health Service, National Institutes of symptoms of gallbladder disease. vestigations falsely negative. Many Health, Office of Alternative Medicine; 1994. Pub- Gallbladder disease was chosen be- other less rigorous assessments of iri- lication NIH 94-066. cause the participating 6 iridolo- dologyhavebeenpublished.Kiblerand 2. Fulder S. Handbook of Complementary Medicine. 14 New York, NY: Oxford University Press Inc; 1988. gists, all leading experts in their field, Sterzing took more than 4000 pho- 3. Barrett S. Quackwatch: your guide to health fraud, had previously indicated that this tographs of more than 1000 patients quackery, and intelligent decisions. Available at: condition was impossible to over- and healthy volunteers and concluded http://www.quackwatch.com. Accessed Septem- ber 1, 1999. look. Stereo color slides were taken that “iridology as a diagnostic tool 4. Federspiel K, Herbst V. Handbuch die andere Medi- of the right iris of each patient, collapses like a house of cards.” Un- zin. Berlin, Germany: Stiftung Warentest; 1996: 315. coded, randomized, and shown to fortunately, some of these early evalu- 5. Sharan F. Iridology: A Complete Guide to Diag- the iridologists. Validity, sensitiv- ations of iridology were methodo- nosing Through the Iris and to Related Forms of ity, specificity, and consistency were logically flawed. The 4 above-cited Treatment. Wellingborough, England: Thorsons 11-14 Publications Ltd; 1989. not significantly different from that studies were, however, adequately 6. Bartholomew RE, Likely M. Subsidising Austra- expected by pure chance. Knips- designed and masked. Therefore, they lian pseudoscience: is iridology complementary child concluded that “iridology is not are most likely to represent the truth medicine or witch doctoring? AustNZJPublic 11 Health. 1998;22:163-164. a useful diagnostic tool.” about iridology. 7. Worrall RS. Pseudoscience: a critical look at iri- Buchanan and coworkers12 took Might iridology be doing any dology. J Am Optom Assoc. 1984;55:735-739. 8. Pokanevych VV. Iridology in Ukraine. Lik Sprava. color photographs of the irides of 4 harm? Waste of money and time are 1998;3:152-156. different patient populations— two obvious undesired effects. The 9. Zubareva TV, Gadakchian KA. The use of iridos- ulcerative colitis (n = 30), coronary possibility of false-positive diag- copy in prophylactic examinations. Oftalmolog- icheskii Zhumal. 1989;4:233-235. heart disease (n = 25), asthma noses, ie, diagnosing—and subse- 10. Simon A, Worthen DM, Mitas JA. An evaluation (n = 30), and psoriasis (n = 30)— quently treating—conditions that of iridology. JAMA. 1979;242:1385-1389. and 1 control group. Controls were did not exist in the first place, seems 11.