Practitioners of iridology claim they can help you just by looking at the iris, the colored portion of the eye, and make diagnostic judgments in relation to systemic aliments. This concept of iris analysis can supposedly detect subconscious tensions, hereditary weaknesses, and states of health and disease. Although they can't really say what’s wrong with you, iridologists claim their unique method can alert you to "imbalances" which can be treated with vitamins, minerals or herbs.

No one knows when this practice of iridology started but Dr. Ignatz von Peczely of Hungary is credited as the promoter of this "science." The story goes that at the age of 10, Peczely accidentally broke an owl's leg and saw a black stripe in its eye. He took care of the bird and later noticed that the stripe slowly disappeared as the owl got well. Peczely eventually became a doctor and saw the same changes in the irises of accident victims. From there, he concluded that all diseases were reflected in the iris of the eye. The Holistic Health Handbook says there are over 10,000 iridologists or iridiagnosticians in Europe and over 1,000 in the United States. The most popular proponent of this art is Dr. Bernard Jensen, an American chiropractor who has written 2 books on the subject.

Iridologists believe the iris is divided into 40 zones, each corresponding to different body parts. These zones and their bodily connections were published 1866. By looking at a particular part of the iris, iridologists say they can determine which body part or organ has a problem. Warning signs include abnormal spots, colors or lines that the iridologist believes reflects all parts of the body, and even the mind and the spirit, providing insight into what is wrong at the moment of examination, what may have been wrong in the past, or even what may go wrong in the future.

The science of iris analysis has never been taught in medical or optometry schools. The shortcomings of iridology were apparent back in the early 1900s when its practitioners failed to identify what was actually wrong with their patients. The method never produced any meaningful scientific results over many years and so it slowly faded away. Today, holistic health enthusiasts have given new life to this old philosophy however current studies still show that nothing has changed and iridology remains an unreliable diagnostic tool in modern eye care.