Photobiomodulation: poised from the fringes.

The most fascinating aspect of science is that there is no permanence; today’s facts are tomorrow’s fallacies. A passage through the annals of the history of medicine showcases fascinating, often gruesome, images of crude surgical procedures and over-simplistic pharmacological ‘‘alchemy’’ that were all held to the epitome of scientific evidence for its time: clinical efficacy, that is, it works in most patients! Procedures such as bloodletting and trepanning were all valid procedures in the practice of medicine in their times. So where does the field of photomedicine stand currently? The field of photomedicine encompasses some well-accepted modalities in modern medicine such as phototherapy (ultraviolet [UV] based), extracorporeal photopheresis, photodynamic therapy (PDT), and laser surgical devices. This review will focus on the distinct ‘‘low level’’ applications broadly termed photobiomodulation (PBM) (Fig. 1). It is prudent to point out that inappropriate or careless use of device parameters for PBM can essentially result in PDT effects, perhaps accounting for many inefficacious and negative results observed. Mester’s pioneering work with low level laser therapy (LLLT) revolutionized and started the field, which led to many investigations, mostly as mere observations with broad, often irrational, speculative applications. Burgeoning, often conflicting literature, has unfortunately led to PBM being labeled as a complementary or alternative medicine largely relegated as a pseudoscience (see Table 1 for definitions). But since then, repeated and continuing clinical and research studies by reputed investigators has re-established the merits of PBM as a genuine medical therapy. The field appears to be currently poised as a fringe science moving toward true legitimacy as a protoscience that should eventually, with continued research and validations, progress to be a mainstream science.