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Iridology for diagnosis

Clinical bottom line: Iridology is not a useful diagnostic technique, producing results no better than guessing. Its use is therefore misleading, with a large risk of false-positive and false-negative diagnosis leading to inappropriate treatment or failure to treat.

Iridology is the diagnosis of medical conditions and ‘pre-disease states' through abnormalities of pigmentation in the iris. It is thought that the location of abnormalities or patterns on the iris is associated with the location of the medical condition in the body. There is therefore a detailed map of the iris divided into 60 sectors, each corresponding to an inner organ or bodily function. The central assumption of iridology is that the iris is associated via multiple nerve connections to the organs.

Systematic review

Ernst E. Iridology: a systematic review. Forsch Komplementärmed 1999; 6:7-9.

Date review completed: December 1997

Number of trials included: 4

Number of patients: 385

Control group: patients without the condition under investigation

Main outcomes: correct diagnosis of condition under investigation

Inclusion criteria were controlled, evaluator-blind or double-blind studies of iridology for diagnosis; any language; articles published in peer-reviewed journals.

Reviewers provided a summary of main findings and trials design for included trials.


Kidney disease

One evaluator-blind case controlled study in 143 patients compared diagnosis of patients with creatinine levels of above 1.2 mg/dL (kidney disease) with patients with normal creatinine levels. Evaluators worked from colour photographs of both irides. All cases were evaluated by iridologists and ophthalmologists. In all cases, diagnosis rates were no different to chance, and no data of clinical importance was produced.

Mitral stenosis

One methodologically flawed case controlled study of 23 patients, some of whom had mitral stenosis and some who did not. Photodensitometry (automatic processing of colour images) was used to assess abnormalities in the iris. Although significant differences were observed in the photometric values of a defined area (p>0.05), it is unclear whether evaluators were blind, and the sample size is very small. It was also unclear whether patients and controls were detectably different in other ways, or whether this was a single positive result amongst many negative results (i.e. due to chance/inappropriate statistics).

Inflamed gallbladder disease

One evaluator-blind case controlled study of 39 patients with inflamed gallbladder (with confirmation of diagnosis postoperatively) and no jaundice were age and sex matched with 35 people with no gallbladder disease. Stereocolour slides were taken of the right irides and rated independently by six leading iridologists. Validity, sensitivity, specificity and consistency of diagnosis were not significantly different from chance.

Mixed population

One case controlled study of 145 patients compared 30 patients with ulcerative colitis, 25 with coronary heart disease, 30 with asthma, 30 with psoriasis and 30 age and sex matched controls. Evaluator assessed photographs manually or by computer programme according to criteria and iris charts generated by reputed iridologists. Discrimination between cases and controls was not significantly different from chance.

Adverse effects

Reviewers did not cover adverse effects.

Further reading

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