Iridology is a theory that it’s possible to assess health issues by analyzing changes in the appearance of the iris and pupil of the eye. Proponents believe that marks and colors in the iris can show various illnesses, separate from any kind of problem with the eye itself. Iridology as a technique is based on the idea that each organ in the human body has a corresponding region in the iris. When there’s illness in the body, changes will occur in that section of the eye.
The birth of iridology as a practice is contested. Some claim that iridology was first presented as a medical theory in the 1665 edition of Chromatica Medica by Philippus Meyeus. Meyeus claimed that he had the ability to link health issues with changes in the iris even before physical symptoms of those issues appeared elsewhere in the body.
Others claim that iridology was developed by Ignaz von Peczely in 1881. After noticing a spot in the eye of an owl with a broken leg, von Peczely hypothesized that the two were linked, later testing this theory on other animals and then people. Ignaz von Peczely is generally considered the “father of iridology.”
In the 1950s, American chiropractor Bernard Jensen went on to create an iridology eye chart that is still in use today. Jensen strongly believed in the practice of iridology and encouraged detoxifying the body to support health with natural foods.
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Iridologists generally utilize cameras, flashlights, and microscopes to examine the patient’s iris to detect tissue change, stromal irregularities (stromal cells are connective tissue cells of any organ; they often play a role in cancer growth) and pigment patterns. The results are then compared to an iris chart, which helps to correlate the various parts of the human body with different zones in the iris.
A typical iris chart divides the iris into approximately 60 zones, each corresponding to a different part of the human body. The left eye corresponds to the left half of the body: the right eye, to the right half. Iridologists believe that the details reflected by the iris are generally the changes in the tissues of the corresponding body parts. For example, a spot in the lower right section of the left iris could indicate an issue with the spleen, shoulder, armpit, or pancreas.
For people who subscribe to the practice, many ailments can be diagnosed with iridology:
Hypertension
High blood pressure can lead to severe health problems like heart disease and stroke. Hypertension presents as a distinct ring around the iris of the eye.
Hyperthyroidism
Thyroid issues may cause bulging eyes, and iridologists can track the appearance of eyes over time to notice the changes. Hyperthyroidism (over activity of the thyroid) can cause Graves’ disease and thyroid eye disease, both of which have bulging or inflamed eyes as a common side effect.
Liver damage
Problems with the liver can present as brown spots in the liver section of the iris as well as a yellowing of the whites of the eyes (the sclera).
Inflammation
Small dots or broken lines in the iris point to irritation and signs of inflammation. Using the iris chart, iridologists can infer what part of the body is experiencing inflammation.
Weakened immune system
When white markings are present in the iris, an iridologist may interpret this as the sign of a weakened immune system.
Naturopaths and holistic wellness practitioners have been determining health needs based on iridology for years, but is the practice legitimate? Most doctors and scientists agree on an answer: Not really.
In the wider medical community, iridology isn’t typically practiced. Besides the fact that extraordinarily little scientific research has been done into iridology, most doctors opt for tests that can more accurately diagnose illness in a specific body part.
A study from 1999 found that “iridology’s efficacy was not supported by scientific evaluations.” Researchers performed another study in 2000 that came to a similar conclusion: “Iridology has shown to be of little benefit to anyone. Patients and therapists should be discouraged from utilizing iridology, since it has the potential to cause personal and financial harm.”
The main controversy surrounding iridology is related to the irises themselves. It’s been proven that the iris does not change in any substantial way during our lives. This is excluding minor pigment changes newborn babies often experience, advanced age, and injury to the eyes. In fact, the stability of the iris's appearance is what makes biometric technology – like the retinal and facial recognition scans that unlock our phones – so secure.
There’s still much debate about the legitimacy of iridology, though some holistic wellness practitioners swear by the practice. Iridology is generally safe – there’s no harm caused by looking at the eyes – though the dubious science behind the practice can lead to misdiagnoses, unnecessary treatments, and side effects from unneeded therapies. Everybody is different, and if you suspect something is wrong or have visible changes to your irises, you should seek medical attention.