Often referred to as “the window to the soul,” the eyes express joy, sadness, and fear. The iris is the most obvious feature of the external eye, with its color being a major factor in ethnic and familial identity. In fact, eye color has been the topic of many researchers’ works, most notably the geneticist Gregor Mendel.
In recent years, naturopathic practitioners have renewed interest in a disease recognition method that is based on detailing characteristics of the human iris. Iridology represents the study of carefully mapped sections of the iris and the assigned organ systems represented by those areas.1
Iridology, also known as iridodiagnosis, is an alternative medicine technique that uses the colors, patterns, and various other properties of the iris to assess an individual’s general health.2 The technique of iridology is based on the belief that each organ in the human body has a corresponding region in the iris. Thus, the premise is that organ functioning can be examined by simply inspecting the iris.
Iridologists generally utilize cameras, flashlights, and microscopes to examine the patient’s iris in order to detect tissue change, stromal irregularities and pigment patterns. The results are then compared with an iris chart, which helps in correlating the various parts of the human body with different zones in the iris.
A typical iris chart usually divides the iris into approximately 90 zones, each corresponding to a different part of the human body. Iridologists believe that the details reflected by the iris are generally the changes in the tissues of the corresponding body organelle.2
According to proponents of this therapy, iridology is not meant to diagnose illness, but rather to detect impaired organ functions attributable to environmental toxins, poor nutrition, and fatigue.
For iridologists, color variations in the iris (sparkles and rings) carry specific significance and can even indicate whether a suspected condition is acute/inflammatory, chronic/inflammatory, or allergic.2
Some iridologists further divide organ system dysfunction by iris color. They believe that lymphatic-related disease is associated with a blue or blue-gray iris and that these individuals are prone to atopic conditions; hematogenous-related pathology is linked to brown-eyed individuals who are more prone to anemia and endocrine disorders; biliary disease is associated with both blue and brown irises, and is indicative of gastric deficiencies.3
Iridology was used as early as the 17th century in Europe, but the practice gained notice in the United States only in the latter half of the 20th century.1 Despite its long history, there are scarce scientific data to support iridology’s utility.
Out of the four of conditions most commonly assessed by practitioners of iridology (hypertension, cancer, gallbladder disease, and kidney disease), only hypertension earned a strength-of-evidence grade of “C,” while the remaining three conditions ended with very weak showings of “D” levels.3
In one study, researchers explored the overlapping of tumor necrosis factor-alpha (TNF-alpha), hypertension, and specific variations of iris constitution.4 Eighty-seven Korean patients with known hypertension were compared with 79 Korean participants with no known BP concerns.
Individuals were evaluated on iris characteristics, BP, and the presence or absence of the TNF-alpha genotype.4 The study results did not show a statistically significant difference in the genotype and the presence of hypertension, but there was a definite elevation in the hypertensive patients with the iris characteristic denoting cardio-renal connective-tissue weakness.4
In another study of the same patient population, researchers examined study participants for a correlation of iris characteristics and the presence or absence of apolipoprotein-E (apoE).5 There is a well-established relationship between this genotype and vascular diseases, including hypertension.5 In a blind study, patients were examined by iris pattern and then testing for the apoE genotype.5 There was a significant correlation between iris type and hypertension, and an increased percentage of apoE presence in those same hypertensive patients.5
Both these studies were not large enough to support the practice of iridology. Further trials with larger study populations are needed.
Studies on the practice have also typically focused on the potential utility of iridology as a screening tool for cancer. One trial examined age- and gender-matched participants for the possibility of colorectal cancer.6 Twenty-nine patients with known diagnoses of this disease were matched with 29 healthy patients.
The researchers presented photographic slides of each participant’s eyes to two trained iridology practitioners. At the end of the study, the presence of cancer was detected in only 50%-53% of patients, proving no better than random chance.6
In another trial exploring iridology and cancer detection, 68 patients with known cancer and 42 healthy patients were examined by a single, experienced iridologist. With no other information than the visualization of the iris, the practitioner correctly detected only three cases of cancer.7
Because of the noninterventional nature of this practice, there are no contraindications for use. In the United States, there are many organizations for training and education in iridology, but the practice is not regulated by the health-care industry.
Iridology is based on intriguing possibilities, but, to date, evidence-based studies do not support its safety and utility. Some researchers are considering improving the accuracy of the practice by using computer-aided diagnostics. For now, however, the study of the iris for systemic disease indications is far from being a viable clinical tool.
Sherril Sego, FNP-C, DNP, is a staff clinician at the VA Hospital in Kansas City, Mo., where she practices adult medicine and women’s health. She also teaches at the nursing schools of the University of Missouri and the University of Kansas.
- Salles LF, Silva MJ. Iridology: a systematic review. Rev Esc Enferm USP. 2008;42:596-600.
- Buchanan T. An investigation of the relationship between anatomical features in the iris and systematic disease with reference to iridology. Comp Ther Med. 2006;4:98-102.
- Iridology page. Natural Standard website. Available at www.naturalstandard.com/index.asp.
- Yoo CS, Hwang WJ, Hong SH, et al. Relationship between iris analysis and TNF-alpha gene polymorphism in hypertensives. Am J Chin Med. 2007;35:621-629.
- Um JY, Hwang CY, Hwang WJ, et al. Association between iris constitution and apolopoprotein E gene polymorphism in hypertensives. J Altern Complement Med. 2004;10:1101-1105.
- Herber S, Rehbein M, Tepas T, et al. Looking for colorectal cancer in the patients iris? Ophthalmologe. 2008;105:570-574.
- Münstedt K, El Safadi S, Brück F, et al. Can iridology detect susceptibility to cancer? A prospective case-controlled study. J Altern Complement Med. 2005;11:515-519.
All electronic documents were accessed on December 15, 2012.