Wound Phototherapy

Researchers have tested the effects of low-level light therapy (LLLT) using low-power lasers or non-coherent, non-collimated light therapy from light-emitting diodes (LEDs) on wounds for decades, exploring the efficacy of phototherapy treatments for chronic1 and acute2 wounds. Low-level light therapy has received device clearance in the United States for cosmetic improvement of aging or sun-damaged skin, acne, actinic keratoses, non-melanoma skin cancer, improving circulation, and decreasing pain as well as stiffness and muscle spasm. 3 It has been used for dental, dermatologic, neurologic, and chiropractic conditions in Canada, Europe, and Asia for several years.4 There are few adequately powered, double-blind randomized clinical trials (RCTs) carefully evaluating energy dose-response of each color or wavelength of LLLT. Typical ranges of LLLT include infrared light waves (800-1200 nm, penetrating 5-10 mm of tissue), red (630-700 nm, penetrating 2-3 mm), yellow (570-590 nm, penetrating 0.5-2 mm), and blue to ultraviolet (400-170 nm, penetrating ⟨ 1 mm).3 Low-level light therapy is delivered at various power densities (W/cm2), time durations, and duty cycles, accumulating as energy absorbed over time, called fluence (J/cm2). The variety of wound outcomes in response to differing LLLT parameters used to stimulate various aspects, depths, and types of tissue injury can be confusing. In this installment of Evidence Corner, a systematic review5 of LED effects on dermatologic conditions and wounds and a second on LLLT effects on diabetic foot ulcers (DFUs)1 add clarity to LLLT effects on some aspects of wound management.