What Is It?
Iridology is the study of the colored part of the eye (called the iris) to determine potential health problems. Iridologists believe that changing patterns and markings in the iris can be used to reveal emerging conditions in every part of the body and to identify inherited weaknesses that may lead to physical and emotional disorders.

Iridology cannot detect a specific disease. Rather, it is a preventive practice that helps people to understand their basic health issues so that they can seek treatment, if necessary, from the appropriate specialist. According to iridologists, if a health problem is detected at an early stage, something can then be done to prevent it from becoming a full-blown disease.

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, 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. (The Pastor Felke Institute in Heimshiem, Germany, is currently one the leading centers of iridologic research and training, and carries on Felke's work.) In addition, German naturopath Josef Deck's books Differentiation of the Iris Signs and Elements of Irisdiagnosis, 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, most American iridologists have been trained using Jensen's techniques.

How Does It Work?
The basis of iridology is a holistic concept well accepted in other fields of alternative medicine, namely that when examined correctly, each part of the body contains information about other parts of the body. In chiropractic medicine, for example, misalignments in the spine are used to diagnose and treat diseases of the internal organs. In Chinese medicine, examinations of the pulse and tongue are regularly included in the diagnostic process. Iridolgists believe that as a degenerative disease slowly develops, the iris will reflect these changes.

Conventional physicians also routinely examine the eye for evidence of internal disease. Using an ophthalmoscope to look at the retina of the eye, a doctor can see how diseases such as diabetes or high blood pressure are affecting blood vessels. Likewise, a close examination of the iris can give information about high cholesterol and certain metabolic ailments.

Iridologists contend that conventional physicians woefully underutilize the iris as a source of information about an individual's health status. They point out that the iris itself is one of the most complex organs in the human body. When a photograph of the iris is enlarged, iridologists claim they can get a view of an ultrafine membrane of connective tissue that shows signs of degenerative diseases well before their presence is manifested in larger organs.

Over the years, many iridology texts have "mapped" segments of the iris to correspond with various internal organs. While this concept is accepted by most American-trained iridologists, it continues to be debated among European practitioners. Although the European iridologists believe that analysis of the eye can indicate a propensity for disease, they point to the lack of evidence for any anatomical correspondence between sections of the iris and specific body parts.

Most American-trained iridologists, however, continue to maintain that the iris is connected to the brain and acts as a control panel, giving readouts on conditions in the various parts of the body. Because thousands of nerve endings make up the iris, they contend, the eye can indeed provide a system of connections to the rest of the body.

What You Can Expect
The iridologist will examine the irises of your eyes using either a slitlamp (an expensive piece of equipment also employed by optometrists and ophthalmologists) or just a penlight and magnifying glass. Many iridologists will also obtain photographs of your iris with a specially designed camera, then considerably enlarge the photos so that the iris appears about the size of a dinner plate. (This can be a rather dramatic sight, allowing you to appreciate the complexity of the iris's structure. With its numerous fibers and colors, the iris is as unique as your fingerprints.) The process is completely painless, safe, and noninvasive.

While examining your irises, both in-person, and later when reviewing the photographs, the iridologist will look for subtle signs of developing illness, such as symptoms of stress or a build-up of toxins. Depending on the practitioner's training, and whether he accepts of the concept of "mapping," eye charts may be consulted to determine problems in corresponding internal organs.

The examination and consultation typically will last about an hour. Unless your iridologist is a licensed physician, you will not be diagnosed with any specific disease. You will, however, be told about any risk factors and given preventive health-care measures to follow.

Many iridologists practicing in the United States are trained in another complementary medical specialty, frequently chiropractic, homeopathy, or naturopathy. In those states where they are licensed to do so, such a practitioner may be able to give a diagnosis and prescribe treatment.

Health Benefits
Because iridology is not a treatment therapy, but rather a way of detecting underlying signs of developing disease, iridologists will let you know about your overall health as well as any trends you may be experiencing toward illness. In this way, their goals are similar to those of all preventive medicine--to recognize health problems at their earliest stages and to suggest ways to keep disease from developing.

One problem with iridology, especially in the United States, has been a lack of adequate training among most of the individuals purporting to be iridologists. Many of the courses in iridology are little more than a weekend long, culminating in a "certification." And even though some licensed chiropractors and naturopaths may practice iridology, their education, by European standards, is often inadequate.

Moreover, marketing companies promoting supplements sometimes offer crash courses in iridology to their distributors. The goal, of course, is to encourage treatment using the company's products. The risk of overdiagnosis then may become a problem, since the practitioner now has secondary motives to "find" conditions on iris examination that are treatable with the products he's paid to recommend.

Because iridology is frequently performed by inadequately trained amateurs, it has not fared well in evidence-based medical studies. The end result is that there is very little published research on iridology (except in iridology journals), and what exists is inconclusive.

Two mainstream scientific studies testing iridologists' abilities to detect gallstones and kidney infection, published in the British Medical Journal and the Journal of the American Medical Association respectively, concluded that iridology was not helpful for either problem. A recent meta-analysis went further and said that iridology was "not useful and potentially harmful." However, professional iridologists have faulted these studies for attempting to diagnose conditions that simply cannot be revealed by their methods.

How To Choose a Practitioner
In the United States, the practice of iridology is totally unregulated or licensed by any governmental agency or professional organization. Anyone can claim to be an iridologist with training that ranges from a couple of days to a full course in naturopathic medicine.

Practitioners trained by the Institute of Applied Iridology (IAI) in Laguna Beach, California, have an education program modeled after the European style of practice. Theirs is a detailed course (72 hours of classroom study, held over several weekends) culminating in both oral and written examinations with certification, if successful. Naturopaths trained at Bastyr University in Kenmore, Washington, can also avail themselves of an elective course in iridology similar to that given by the IAI.

If you are seeking an iridologist, try to find one who is either certified by the Institute for Applied Iridology or by the International Iridology Research Association (IIRI) in Solana Beach, California. Unfortunately, among the approximately 10,000 individuals calling themselves iridologists in the U.S., no more than 150 or so actually meet the standards of certification.

Cautions
Iridology is generally safe, noninvasive, and painless. However, it has not been proven to be an effective health-care treatment and shouldn't be used as a substitute for conventional treatment. If the iridologist uncovers anything of concern, make sure you discuss these findings with your primary-care physician.

Some critics point out that the theories of iridology were originally developed in northern Europe, where most people have blue eyes. They suspect that because of this, iridologists have a tendency to see blue eyes as the standard for good health and to misinterpret findings in people who have brown or hazel eyes.