Low-level laser therapy

Lore & Background

The history of low-level laser therapy begins with Faroese physician Niels Finsen, considered the father of modern light therapy, who used red light to treat smallpox lesions and received the Nobel Prize in Physiology or Medicine in 1903. However, scientific evidence for some of his treatments is lacking, and later eradication of smallpox and development of antibiotics for tuberculosis rendered light therapy obsolete for those diseases. Hungarian physician and surgeon Endre Mester (1903–1984) is credited with discovering the biological effects of low-power lasers a few years after the 1960 invention of the ruby laser and the 1961 invention of the helium–neon (HeNe) laser. Mester accidentally discovered that low-level ruby laser light could regrow hair during an attempt to replicate an experiment on reducing tumors in mice; the faulty laser failed to affect tumors but caused faster hair regrowth in shaved mice. He published those results in 1967 and later showed that low-level HeNe light could accelerate wound healing in mice. By the 1970s, he was treating people with skin ulcers, and in 1974 he founded the Laser Research Center at the Semmelweis Medical University in Budapest, where he worked for the remainder of his life. His sons carried on his work and brought it to the United States.

Reader's Guide

Low-level laser therapy represents a significant intersection of photochemistry and medicine, relying on the Grotthuss-Draper law: light must be absorbed by a chemical substance—in this case, the respiratory enzyme cytochrome c oxidase in mitochondria—for a photochemical reaction to occur. Its applications span human and veterinary medicine, including musculoskeletal conditions like osteoarthritis and rheumatoid arthritis, wound healing, and prevention of oral mucositis in stem cell transplant recipients. However, the therapy's effectiveness remains under investigation, with mixed evidence. In veterinary use, research is sparse and generally low quality, with most studies small and lacking controls. The FDA has taken action against fraudulent marketing, such as the 2014 injunction against QLaser for claiming treatment of over 200 diseases including cancer and HIV/AIDS, leading to a criminal conviction and a 12-year prison sentence for the owner. Insurance coverage is limited: Blue Cross Blue Shield Association and Aetna cover only prevention of oral mucositis. The therapy's legacy is one of cautious promise tempered by regulatory scrutiny and the need for more rigorous clinical trials.

Did You Know?

• Endre Mester accidentally discovered low-level laser therapy's hair-regrowth effect in 1967 while trying to replicate an experiment on reducing tumors in mice with a faulty laser.
• The therapy relies on the Grotthuss-Draper law, the first law of photochemistry, requiring light absorption by cytochrome c oxidase in mitochondria.
• In 2018, QLaser owner Robert Lytle pleaded guilty to conspiracy to introduce misbranded medical devices and was sentenced to 12 years in prison.
• Transcranial low-level light therapy can use both LED and laser light, as both can penetrate skin and soft tissues; penetration depth depends on wavelength and power, not on coherence.