Photomedicine is a medical field that involves using light for therapeutic or other medical reasons. Researchers in this field also study how light impacts the human body, including positive and negative effects. Though the field originated in the late 1800s, major technological developments in photomedicine occurred in the 1990s, along with public demand for safer and more effective cancer treatment. However, photomedicine has several applications beyond cancer, including hair loss, surgery, and skin disorders.
There are multiple applications of photomedicine for cancer treatment. One of these include photodynamic therapy, which involves using light to trigger a chemical reaction in abnormal or mutated cells, such as cancerous cells. The photochemical reaction occurs through the interaction between light, light-sensitizing agents (also known as photosensitizers), and oxygen, and ultimately aids in destroying the cells. Photodynamic therapy (PDT) strategies are also utilized to activate the human immune system against cancer. Stronger immune systems may help in eliminating clusters of malignant cells remote from the primary tumor. The four main methods of photoimmune strategies include: low dose PDT with immune adjuvants, photoimmunotherapy, PDT vaccines, and systemic light treatments.
Specific disorders that impact hair retention, such as alopecia, pattern hair loss, and natural hair loss caused by genetics can be alleviated through photomedicine. Low-level laser therapy applied to the areas of skin where hair is lacking can stimulate hair growth by shifting epidermal stem cells in the hair follicles to the anagen phase. This treatment can also be applied to increase hair density, thickness, and fullness.
Surgeries can be guided by photomedicine through fluorescent lights. In this process, different types of photosensitizers illuminate abnormal cells or diseased tissue. This allows surgeons to visualize in real time which tissue or cells need to be surgically removed. Photomedicine is being applied to surgery in the form of safe and effective lasers that can be used to cut through or otherwise remove unwanted objects within the body.
A variety of skin disorders can be treated through photochemotherapy or narrowband ultraviolet B (UVB) rays, including: eczema, psoriasis, pruritus, graft-versus- host disease, and vitiligo. In addition, new ultraviolet A (UVA) treatments have been developed to treat additional disorders such as: atopic dermatitis, scleroderma, scleredema, and nephrogenic systemic fibrosis. In these treatments, specific wavelengths of different types of light, depending on the treatment, are applied to the affected skin areas, sometimes in conjunction with an oral medication that
sensitizes the skin to light.
Avci, P, et al. “Low-Level Laser (Light) Therapy (LLLT) for Treatment of Hair Loss.” Lasers in
Surgery and Medicine., U.S. National Library of Medicine, Feb. 2014.
Jimenez, Joaquin J., et al. “Efficacy and Safety of a Low-Level Laser Device in the Treatment of
Male and Female Pattern Hair Loss: A Multicenter, Randomized, Sham
Device-Controlled, Double-Blind Study.” American Journal of Clinical Dermatology,
Springer International Publishing, 29 Jan. 2014.
Legarde, Caroline M. “Phototherapy.” Johns Hopkins Dermatology: Photomedicine, Johns
Hopkins, 30 Aug. 2016.
“What Is Photomedicine?” Photoimmune Discoveries, Photoimmune Discoveries, n.d.
“Why Light for Medicine?” The Wellman Center for Photomedicine: About Us: Why Light?,
Massachusetts General Hospital, n.d.