Iridology

We are writing to comment on the recent article by Ernst¹ concerning the failure of iridology to stand up to any rigorous scientific review. In a historical accounting of the discovery and development of iridology,² Ignatz von Peczely of Egervar, Hungary, is credited with the discovery of iridology by observing the development of a dark iridal stripe in the eye of an owl subsequent to breaking one of its legs. This dark stripe then became altered in appearance, presumably in association with a healing process in the leg. No such systematic association has ever been observed by veterinary ophthalmologists or by veterinarians expert in wild and cage bird medicine. Raptors do have a very high frequency of ocular lesions largely attributable to traumatic episodes. In one study,³ approximately 1 of every 4 birds brought in for medical attention to rehabilitation centers had an ocular lesion of some form. Anterior segment lesions were more common than posterior segment lesions with hyphema being the single most common ocular lesion. For a period of several years, we served as the clinicians for services overseeing the examination and care of hundreds of free-living wild raptors that had sustained injuries or illness, resulting in sufficient debility to be captured and delivered for medical attention. Broken limbs were frequently observed, but never resulted in any change in iridal appearance, and many birds with iridal lesions and no associated systemic lesions were observed. It seems that the historical foundations of iridology lack any validity. It also seems that the overzealous interpretation of iridal appearance is not limited to humans, as Web sites now exist extolling the virtues of this practice in diagnosing veterinary patients.