Red Light Therapy for the Treatment of Retinal Diseases(2)

Red light had been valued in the practice of medicine since antiquity^[1]. The utility of red light appears to be “re-discovered” at the end of the 18^th century by Finsen^[2]–^[4] who later became to be known as the “father of contemporary phototherapy” for his astonishing achievements of curing skin disorders such as small blisters using red light and lupus vulgaris using UV light. These successes won him the 1903 Nobel Prize in Medicine and Physiology “in recognition of his contribution to the treatment of diseases, especially lupus vulgaris, with concentrated light radiation, whereby he has opened a new avenue for medical science”^[5].

It is believed that the medical usefulness of FR/NIR light had been “re-discovered” for a second time upon the invention of the laser in the 1960s^[1],^[6]. It happened thanks to an unexpected research outcome where Mester et al^[7] attempted to use laser-derived 694 nm light to induce skin cancer in mice. Prior to the experiment, the mouse fur atop the location where the light would be applied was shaved. To the researchers' surprise, the subsequent 694 nm light treatment not only failed to induce cancer but instead caused the fur to re-grow faster in the treated mice compared with the untreated control. This was the first documented demonstration of “laser biostimulation”^[6]. Ever since, the study and application of FR/NIR light had been of sustained interest in the medical community (recently reviewed by Chung et al^[8], Rojas and Gonzalez-Lima^[9], and Peplow et al^[10]).

Over the years, the number of conditions amenable to PBM has greatly increased and their diversity is truly amazing, with the majority having been explored in both animal models and human patients. These range from wound healing, including diabetic ulcers^[10]–^[13] to pain control for neurologic neck pain^[14] and pain from chronic joint disorders^[15] to promotion of the regeneration and functional recovery of tissues with poor healing potential such as injured peripheral^[16]–^[17] and optical nerves^[9],^[18], recovery following stroke^[19] and other central nervous system damage such as traumatic brain injury^[20]. Further, there are a number of applications of PBM to treat retinal disorders, which are the focus of this review and include AMD^[21], diabetic retinopathy^[22], and amblyopia^[23], among many others. Although initially it was believed that the light used in PBM had to be coherent and polarized like light produced by the He-Ne laser, these properties are no longer considered essential such that devices containing LED arrays are now widely used in photo-medicine at only a fraction of the cost for a laser^[1].

Excerpted from:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4768515/