History of Iridology
(Excerpts obtained from “Iridology, Alternative Therapies”) 

The idea that the eyes are a mirror to the body is an ancient one: The Greek physician, Hippocrates, was known to examine patients' eyes for signs of illness. It wasn't until 1670, however, that the first actual medical reference to iridology as a diagnostic tool appeared in German physician Phillipus Meyens' book, Chiromatica Medica.

In the late 19th century, Hungarian physician, Ignatz von Peczely, and Swedish clergyman, Nils Liljequist, independently advanced theories connecting the markings of the iris with tendencies toward specific ailments. Both men's interests stemmed from experiences in their childhoods.

As a boy, Peczely accidentally broke the leg of an owl and then noticed a black mark that subsequently appeared in the bird's iris. Later, in his medical practice, he noted similar marks in the eyes of his human patients who'd suffered a fracture. For his part, Liljequist contracted malaria in his teens and was treated with quinine and iodine. As the drugs accumulated in his system, he noticed that his blue eyes were turning a darker color. After he later became a homeopath, he found similar reactions in his patients as well.

Today, modern iridology is practiced far more widely in Europe than in the United States or Canada, with Germany contributing most of the research in the field during the past century. This is in part due to the influence of the German minister, Pastor Felke, who developed a form of homeopathy for treating specific iris indications in the early 1900s. In addition, German naturopath, Josef Deck's books Differentiation of the Iris Signs and Elements of Iris Diagnosis, first published the 1930s, continue to be the standard textbooks on the subject.

Iridology first became known in the United States in the 1950's, when Bernard Jensen, an American chiropractor, began giving classes in his own method, which mainly concentrates on iris color, the body's exposure to toxins, and use of natural foods as detoxifiers. Although Jensen's concepts have never been fully accepted by his European counterparts, many American and Canadian iridologists have been trained using Jensen's techniques.