Even the dictionary supplement of the World Book Encyclopedia Yearbook gives credibility to iridology by the definition it supplies:

Until recently iridology has been practiced primarily by chiropractors, naturopaths, and homeopaths. But in recent years, many other new age therapists have begun to use iridology and even some physicians and optometrists have become converts. One alternate medical guide observes, "Many therapists, including osteopaths, acupuncturists, herbalists and homeopaths, use iridology as an aid to diagnosis alongside their other physical tests."² According to International Iridologists in Escondido, California, there are an estimated ten thousand practitioners of iridology in Europe and over one thousand in the U.S.

One example of a medical convert to iridology is optometrist Dr. James Carter. He became a believer by reading leading iridologist Bernard Jensen’s text on iridology and testing the practice for himself. He has proceeded to teach iridology to numerous doctors in the San Francisco area and is conducting studies at San Francisco General Hospital. His research there involves "several double blind studies on the accuracy and reproducibility of the schematic or homunculus (miniature body) relationship of the iris fibers and the body, and also some study into the possible pathways involved in iris changes as a result of systemic disease."³

The iridologist claims he is able to diagnose the physical condition of the body through examining the iris, the colored part of the eye. He also claims that he can diagnose the probability of future illnesses and diseases by the same method.

Iridology is based upon the idea that each organ of the body is represented by a corresponding area within the iris. The left iris represents and is a picture of the left side of the body; the right iris represents and is a picture of the right side of the body. Thus, the head is at the top of the iris, the feet are at the bottom; the areas in between the head and the feet are arranged top to bottom in rough parallel sequence to their arrangement in the human body. Organs that are paired or symmetric, such as the kidneys and nose, are found in both irises.

Iridologists characteristically give scientific sounding descriptions of how iridology allegedly operates. Jessica Maxwell in The Eye-Body Connection, a self-help book on iridology, claims that "The basis for iridology is the neuro-optic reflex, an intimate marriage of the estimated half million filaments of the iris with the cervical ganglia of the sympathetic nervous system. The neuro-optic reflex turns the iris into an organic etch-a-sketch that monitors impressions from all over the body as they come in."⁴

Optometrist Dr. James Carter and chiropractor Dr. Bernard Jensen also supply scientific sounding explanations of how iridology works.⁵ But the claimed scientific foundations are not justified as many doctors of optometry and ophthalmologists have pointed out.⁶ Detailed neuro-anatomical study of the eye and central nervous systems prove there is no evidence for the alleged neurological pathways required for such a powerful relay of information. Russell S. Worrall is assistant clinical professor in the School of Optometry at the University of California, Berkeley. Citing Adlers Physiology of the Eye (1975, pp. 367-405) he comments:

Paul Reisser, M.D., points out that:

Nevertheless, the scientific sounding descriptions impress many people and convince them that iridology is a legitimate diagnostic technique.

The idea that a particular organ of the body, in this case the eye, constitutes a miniature version of the entire body is not new. Throughout its glorious history, quack medicine has held that many different body organs constitute a miniature representation of the human body. The human body has been "compressed" and inserted into the outer ear, the nose, face, head, and even the anus and other parts or organs of the body.⁹ Reflexology does the same with the hand or foot, and homuncular or auricular acupuncture does the same with the outer ear. In its own manner, chiropractic does the same with the human spine.

Iridology can be traced to ancient Chinese astrological practices, however, according to Dr. Carter, the first precursor published on iridology was Philippus Meyens’ Chiromatica Medica, (Germany, 1670).

Nevertheless, the credit for developing and promoting modern iridology usually goes to Dr. Ignatz von Peczely of Hungary (Discoveries in the Field of Natural Science in Medicine, Hungary, 1880) and Nils Liljequist, a Swedish homeopath and minister (Diagnosis from the Eye, Sweden, 1893).¹⁰

When Ignatz was eleven years old, he made what he thought was an amazing discovery. Being attacked by a mother owl in the woods one day, he was forced to break the bird’s leg to escape. At that very moment he noted a black line running down the iris. He concluded that the break in the owl’s leg had registered in the iris, perhaps an understandable conclusion for a frightened young boy. Nevertheless, this event became the basis for von Peczely’s later development of iridology. Research, however, has proven that breaking an owl’s leg leaves no such mark in the iris and that the lad had probably misinterpreted the visual effect produced by the black inner lining of the upper lid when the owl opens the eye.¹¹

Iridology was introduced into the U. S. in 1904 with the publication of Henry Lahn’s Iridology: The Diagnosis from the Eye (1904). More recent American texts include Iris Diagnosis by a student of Dr. Lahn, Henry Lindlahr; Theodore Kriege’s, Fundamental Basis of Iris Diagnosis, London, 1975; and Bernard Jensen’s The Science and Practice of Iridology, U.S., 1952, and its sequel Iridology: Science and Practice in the Healing Arts, U.S., 1982.

In the U.S., the "father" of American iridology may be considered chiropractor and naturopath Bernard Jensen. By far, he has been the most influential proponent of the practice. Surprisingly, it is often claimed by iridologists that Jensen has supplied the most scientific defense of iridology.

However, this claim cannot be substantiated. In a nutshell, the scientific quality of his books leaves much to be desired. Russell S. Worrall, O.D., Assistant Clinical Professor in the School of Optometry at the University of California, Berkeley, has published works on optical topics in journals such as Review of Optometry, Optometric Monthly, and Journal of the American Optometric Association. In his article, "Iridology: Diagnosis or Delusion," Worrall observes of Jensen’s most recent text, Iridology: Science and Practice in the Healing Arts (vol. 2, 1982), "This volume contains countless misinterpretations of established anatomical and physiological knowledge and includes references to many pseudosciences, such as Kirlian photography and personology."¹² Jensen’s earlier volume contains similar problems, as a perusal will reveal.¹³

Despite the claims of over-zealous followers, Jensen is not a scientist, but a popular new age healer, a fact revealed in his various works, such as Iridology: Science and Practice in the Healing Arts. In this text, he discusses his belief in reincarnation, astral travel, psychic development, and other occultic practices and philosophies.¹⁴ He also confesses his great indebtedness to occultist Manly P. Hall, gurus Sai Baba and Jiddhu Krishnamurti, homeopath V. G. Rocine, occultist and polarity therapy founder Randolph Stone, and those of similar persuasion.¹⁵

In fact, his new age faith in various energy forces, psychic vibrations, and radionics apparently supplied the theoretical basis for his ideas on how iridology allegedly works; "It seemed to me that finer [occult] forces, that functioned as if by direction of some innate intelligence, were operating through the autonomic nervous system."¹⁶

Iridology is shown to be compatible with new age medicine in general. One chart in particular reveals how iridology can be correlated to the practices of Chinese acupuncture and philosophy (as well as Hindu yogic principles and Ayurvedic medicine.¹⁷

Jensen’s new age philosophy is also evident in the section titled "A Deeper Look," giving an extensive bibliography replete with new age texts, several of which originate from the spirit world. Books listed as those "which have helped me" include the standard spirit-inspired theosophical text by medium H. P. Blavatsky, Isis Unveiled; new age bible The Aquarian Conspiracy by Marilyn Ferguson; parapsychologist Jeffrey Mishlove’s The Roots of Consciousness; as well as the spiritistically inspired text A Course in Miracles.

Jensen also lists many books which stress the typical new age mystical energy themes such as psychic Jack Schwartz’ Human Energy Systems; parapsychologist Shafica Karagulla’s study of psychic abilities Breakthrough to Creativity; and chiropractor and occultist David V. Tansley’s Radionics and the Subtle Anatomy of Man.¹⁸

The influence of Jensen upon so many modern American iridologists perhaps explains why much of contemporary U.S. iridology is associated with various occultic arts and practices.