Iridology
For the general entry on Alternative Medicine, click here
The Claims:
Iridology is the belief that each area of the body is represented in a particular part of the iris. The iris is the coloured part of the eye which dilates or contracts the central pupil (which appears black). This determines the amount of light that is let into the eye.
In the study of iridology each portion of the iris in both left and right eyes is divided like a pie into different parts of the body and the iridologist then can determine which part of the body is diseased or not functioning properly. It is also believed that the iris shows a history of past disease and can produce a diagnosis for a disease which will occur in the future, and that preventative measures can then be taken with naturopathic medicine.
The Evidence:
Examination of the eye, including the iris, by a trained physician can at times be an indication of diseases which affect the eye (such as diabetes). However, there is no evidence that each part of the iris represents different organs and parts of the body. Iridology charts (which can vary) are referred to by the iridologist to determine which organ is diseased.
However, in double-blind placebo-controlled studies a trained iridologist has correctly diagnosed the disease only in what would be expected by chance alone. In these studies, iridologists examined the actual iris of diseased and healthy patients, or examined high quality images of eyes and recorded their diagnosis.
In all of these clinical studies using correct scientific procedure the iridologist could not produce a correlation (other than chance) between specific patterns of the iris and the presence or absence of disease.
Conclusion:
Examination of the iris is of no clinical use in diagnosing disease in other parts of the body not relating directly to the eye itself. There has never been a proven correlation between the presence of patterns on the iris and disease in other parts of the body.
The Skeptic’s Dictionary Entry on Iridology
“Is Evaluating Complementary and Alternative Medicine Equivalent to Evaluating the Absurd?” Greasley, P. 2010.
“Can Iridology Detect Susceptibility to Cancer? A Prospective Case-Controlled Study” Münstedt, K., El-Safadi, S., Brück, F., Zygmunt, M. , Hackethal, A., Tinneberg, H-R. 2005.
“Subsidizing Australian Pseudoscience: Is Iridology Complementary Medicine or Witch Doctoring?” Bartholomew, R.E., Likely. M. 1998.
Extraordinary Claims Require Extraordinary Evidence 
Then why is iridology part of Russian curriculum for medical school? Why is it used in Australia and England and highly respected? Because the US medical community is quick to cry snake oil when they feel threatened by natural healing modalities.