Iridology

Iridology is a diagnostic practice claiming that iris patterns reveal diseases or conditions elsewhere in the body. Controlled research has not established reliable diagnostic accuracy.

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Iris chart: A diagram assigning iris regions to organs or body systems for use in iridology. Iridology practitioners use these charts to interpret iris features as signs of bodily conditions.
Simon study of iridology: A 1979 controlled study that tested whether iridologists could identify kidney disease from iris photographs. Its blinded comparison directly tested an organ-specific claim made by iridology.
Ophthalmoscopy: Examination of the interior of the eye, especially the retina and optic nerve, using an ophthalmoscope. Unlike iridology, it assesses visible eye structures for conditions with established clinical relevance.
Ignaz von Peczely: A nineteenth-century Hungarian physician commonly credited with developing an early form of iridology. His writings helped establish the idea that iris markings correspond to bodily organs.
Iris (anatomy): The colored, contractile structure in the eye that controls pupil size and helps regulate incoming light. Iridology treats visible features of this structure as diagnostic signals.
Ernst review of iridology: A 2000 systematic review assessing controlled clinical trials of iridology's diagnostic accuracy. The review found no evidence supporting iridology as a diagnostic method.
Retinal imaging: Methods that capture images of the retina to document or assess eye and systemic disease. Some retinal changes are clinically associated with disease; this does not validate iris maps.
Nils Liljequist: A Swedish homeopath who published an early iris chart in the late nineteenth century. His chart contributed to iridology's development alongside von Peczely's work.
Diagnostic test: A procedure or measurement used to identify, confirm, or rule out a disease or condition. Iridology presents iris inspection as a diagnostic test, making test accuracy central to its claims.
Controlled clinical trial: A study that compares an intervention or test with a control under planned conditions. Blinding and comparison with established diagnoses help separate diagnostic skill from expectation.