Photobiomodulation (PBM), also known as low-level laser therapy (LLLT), is a non-invasive light therapy. It uses specific wavelengths of red and near-infrared light applied to tissues or lesions to elicit therapeutic benefits. PBM aims to improve tissue healing, reduce inflammation, and alleviate pain in both acute and chronic conditions.
How Photobiomodulation Works
Photobiomodulation works by light photons being absorbed by specific molecules within cells, known as chromophores. A primary chromophore targeted by PBM is cytochrome c oxidase (CcO), an enzyme located in the mitochondria. When red and near-infrared light (600 to 1000 nanometers) is absorbed by CcO, it triggers a cascade of biochemical events. This enhances the mitochondrial electron transport chain, leading to increased adenosine triphosphate (ATP) production, the main energy currency of the cell.
Increased ATP production helps restore cellular function and promote cellular regeneration. In stressed or damaged cells, nitric oxide (NO) can bind to CcO, inhibiting ATP production. Light absorption helps dissociate this inhibitory nitric oxide, allowing oxygen to bind more effectively and reactivating ATP synthesis. This process also modulates reactive oxygen species (ROS), which, at balanced levels, play a role in cell signaling and can promote healing.
The release of nitric oxide from the mitochondria can also lead to localized vasodilation, improving blood flow and oxygen delivery to the treated area. These cellular and molecular changes collectively contribute to anti-inflammatory effects, pain reduction, and the promotion of tissue repair. Unlike surgical lasers, PBM lasers operate at low power densities (10 to 500 mW) and do not produce a heating effect, making the process photochemical rather than thermal.
Common Applications of PBM Lasers
PBM lasers are applied across a wide array of conditions, leveraging their ability to reduce pain, diminish inflammation, and promote tissue healing. In pain management, PBM is used for musculoskeletal issues such as arthritis, back pain, and sports injuries like sprains and strains. It can alleviate both nociceptive and neuropathic pain, with some studies showing benefits for conditions like fibromyalgia and postherpetic neuralgia.
PBM is a recognized therapy for wound healing, including diabetic ulcers, venous ulcers, and burns. It improves scar appearance, notably for hypertrophic and keloid scars, by enhancing tissue repair processes. PBM also supports nerve regeneration, which is particularly relevant in cases of nerve damage or neuropathies.
The applications extend to managing side effects of cancer therapies, such as oral mucositis, a common and painful inflammation of the mouth lining caused by chemotherapy or radiation. PBM can also be used to address lymphedema, a swelling that can occur after cancer treatment, and radiation dermatitis. Emerging areas of research include the potential for PBM in neurological conditions, with investigations into its effects on mild cognitive impairment, depression, and other brain injuries. For skin rejuvenation, PBM can promote cellular health and improve skin appearance.
Safety and Important Considerations
PBM lasers are generally considered safe, with minimal reported side effects. Any side effects are typically mild and temporary, such as a sensation of warmth or slight redness in the treated area. However, it is important to use appropriate eye protection for both the patient and the practitioner during PBM laser treatments, as direct exposure to laser light can be harmful to the eyes.
Certain contraindications exist for PBM therapy. Treatment directly over a known primary carcinoma or secondary metastasis is generally avoided, though it may be considered for palliative pain relief in terminal stages or to mitigate side effects of cancer therapies like mucositis, always with a physician’s permission. PBM is also not recommended directly over the developing fetus during pregnancy due to a lack of comprehensive safety data, although it may be used for other conditions like back pain in pregnant individuals.
Individuals with photosensitive epilepsy should exercise caution with pulsed visible light, as it could potentially trigger seizures. It is also suggested to avoid applying high-intensity lasers directly over the thyroid gland. For effective and safe treatment, it is important to seek care from qualified professionals who can accurately diagnose the condition and select appropriate device parameters, including wavelength and power, to ensure optimal therapeutic outcomes.