“Let there be light.” Research on phototherapy, light therapy, and photobiomodulation for healing – Alternative therapy becomes mainstream

Light Therapy in Chronic Migraine

PURPOSE OF REVIEW

This review assesses the effectiveness and safety of light therapy, particularly green light therapy, as an emerging non-pharmacological treatment for chronic migraine (CM). It aims to highlight alternative or complementary approaches to traditional pharmacological remedies, focusing the need for diverse treatment options.

RECENT FINDINGS

Despite sensitivity to light being a defining feature of migraine, light therapy has shown promising signs in providing substantial symptom relief. Studies have provided insights into green light therapy's role in managing CM. These studies consistently demonstrate its efficacy in reducing the frequency, severity, and symptoms of migraines. Additional benefits observed include improvements in sleep quality and reductions in anxiety. Importantly, green light therapy has been associated with minimal side effects, indicating its potential as a suitable option for migraine sufferers. In addition to green light, other forms of light therapy, such as infrared polarized light, low-level laser therapy (LLLT), and intravascular irradiation of blood (ILIB), are also being explored with potential therapeutic effects. Light therapies, especially green light therapy, are recognized as promising, safe, and non-pharmacological interventions for treating CM. They have been shown to be effective in decreasing headache frequency and enhancing the overall quality of life. However, current studies, often limited by small sample sizes, prompt more extensive clinical trials to better understand the full impact of light therapies. The exploration of other light-based treatments, such as LLLT and ILIB, warrants further research to broaden the scope of effective migraine management strategies.

What can we learn from treatments of oral lichen planus?

Oral lichen planus (OLP), a T-lymphocyte-mediated disease of the oral mucosa, has a complex pathogenesis that involves a number of factors. The disease is characterized by recurrent episodes and requires continuous follow up, and there is no curative treatment available. Erosive lichen planus, among others, has a risk of malignant transformation and requires standardized treatment to control its progression. Different clinical subtypes of oral lichen planus require appropriate treatment. Pharmacological treatments are the most widely available and have the greatest variety of options and a number of novel pharmacological treatments are presented as highlights, including JAK enzyme inhibitors. The second is photodynamic therapy, which is the leading physiological treatment. In addition, periodontal treatment and psychological treatment should not be neglected. In this review, we briefly discuss the most recent developments in therapies for oral lichen planus after summarizing the most widely used clinical treatments, aiming to provide different proposals for future clinical treatment.

Twelve-Month Follow-Up of Different Dentinal Hypersensitivity Treatments by Photobiomodulation Therapy, Nd:YAG and Nd:YAP Lasers

In this retrospective study, data for three different laser-assisted approaches for the management of dentinal hypersensitivity (DH) was collected (n = 920 teeth). In total, 387 teeth were treated with photobiomodulation (PBM) therapy with 660 nm red light laser (PBM group), 327 were treated with the Nd:YAG laser (1064 nm) and 206 were treated with the Nd:YAP laser (1340 nm). To assess the effectiveness of each treatment, a visual analogue scale (VAS) was used, where zero represented no pain at all and ten represented the greatest pain. VAS was used before (T0), immediately after (T1), one week after (T2), four weeks after (T3), six months after (T4) and one year after treatment (T5). Means and standard deviations of VAS at different follow-up times were calculated. Values were compared within and between groups. Statistical significance was considered to be achieved when p-value was less than 0.05. Confidence level was proposed to be 99% with a P value lower than 0.001. Within groups, a statistically significant reduction was obtained when the mean value of VAS at T0 was compared with T5. At T5, the PBM group had the highest reduction of VAS (with mean value of 0), while the Nd:YAG and Nd:YAP groups had scores of 1.065 ± 0.674 and 4.665 ± 0.674, respectively. Conclusion: this retrospective study showed that PBM therapy and irradiation with Nd:YAG and Nd:YAP lasers are effective in managing DH pain. However, PBM therapy was the only procedure that showed complete pain relief at six and twelve months after treatment.

Photobiomodulation Therapy vs. Corticosteroid for the Management of Erosive/Ulcerative and Painful Oral Lichen Planus. Assessment of Success Rate during One-Year Follow-Up: A Retrospective Study

Photobiomodulation (PBM) therapy is a promising approach for the management of inflammatory conditions and autoimmune lesions, such as oral lichen planus (OLP). The aim of this retrospective study was to assess the effectiveness of PBM in the management of painful and erosive/ulcerative OLP and to compare it with the standard of care that is the topical application of corticosteroids. 96 patients were included with erosive and painful OLP. 48 patients received PBM therapy and 48 received corticosteroids. Data was collected retrospectively on pain using the visual analogue scale; clinical aspects of lesions were assessed with the REU score, and the recurrence rate was noted. One session of PBM therapy with a helium-neon red light (635 nm) was carried out every 48 h for 6 weeks. Treatments were mainly made in contact mode, using a fiber with a diameter of 600 µm (0.6 mm). The output power of the laser beam was calibrated by a power meter. A delivered power of 0.1 W was used for 40 s in a continuous wave (CW), corresponding to a delivered energy of 4 J. The delivered energy density related to the fiber diameter was 1415 J/cm². Each treated point was considered as 1 cm² of diameter. PBM therapy within these parameters was carried out on each point until the totality of the lesion was covered, including the non-erosive OLP area. Furthermore, healthy mucosa within 5 mm of the lesion was also irradiated with the same conditions. This PBM treatment was performed during 6 consecutive weeks. The topical corticosteroid treatment consisted of cortisone application to cover the OLP 3 times/day for 6 weeks. Follow-up was made at 6 weeks and at 3, 6 and 12 months. After 6 weeks, both groups showed complete absence of pain, and a complete disappearance of ulcerative/erosive areas. No significant difference was found for both groups concerning the recurrence rate of erosive OLP during the follow-up period; values were 0% at 6 weeks for both groups and 79% and 87.5% for the corticosteroid and PBM group, respectively, at 12 months of follow-up. PBM is effective for managing OLP and is significantly similar to topical corticosteroids without any need for the use of medication and with no reported side effects.

Mechanisms and Pathways of Pain Photobiomodulation: A Narrative Review

A growing body of evidence supports the modulation of pain by light exposure. As such, phototherapy is being increasingly utilized for the management of a variety of pain conditions. The modes of delivery, and hence applications of phototherapy, vary by wavelength, intensity, and route of exposure. As such, differing mechanisms of action exist depending upon those parameters. Cutaneous application of red light (660 nm) has been shown to reduce pain in neuropathies and complex regional pain syndrome-I, whereas visual application of the same wavelength of red light has been reported to exacerbate migraine headache in patients and lead to the development of functional pain in animal models. Interestingly visual exposure to green light can result in reduction in pain in variety of pain conditions such as migraine and fibromyalgia. Cutaneous application typically requires exposure on the order of minutes, whereas visual application requires exposure on the order of hours. Both routes of exposure elicit changes centrally in the brainstem and spinal cord, and peripherally in the dorsal root ganglia and nociceptors. The mechanisms of photobiomodulation of pain presented in this review provide a foundation in furtherance of exploration of the utility of phototherapy as a tool in the management of pain. PERSPECTIVE: This review synopsizes the pathways and mechanisms through which light modulates pain and the therapeutic utility of different colors and exposure modalities of light on pain. Recent advances in photobiomodulation provide a foundation for understanding this novel treatment for pain on which future translational and clinical studies can build upon.

Green Light Antinociceptive and Reversal of Thermal and Mechanical Hypersensitivity Effects Rely on Endogenous Opioid System Stimulation

Benefits of phototherapy were characterized in multiple diseases including depression, circadian rhythm disruptions, and neurodegeneration. Studies on migraine and fibromyalgia patients revealed that green light-emitting diodes (GLED) exposure provides a pragmatic and safe therapy to manage chronic pain. In rodents, GLED reversed hypersensitivity related to neuropathic pain. However, little is known about the underlying mechanisms of GLED efficacy. Here, we sought to understand how green light modulates the endogenous opioid system. We first characterized how exposure to GLED stimulates release of β-endorphin and proenkephalin in the central nervous system of male rats. Moreover, by individually editing each of the receptors, we found that µ- and δ-opioid receptors are required for green light's antinociceptive effect in naïve rats and a model of HIV-induced peripheral neuropathy. We investigated how GLED could increase pain thresholds, and explored its potential in reversing hypersensitivity in a model of HIV-related neuropathy. Through behavioral and gene editing approaches, we identified that green light provides antinociception via modulation of the endogenous opioid system in the spinal cord. This work identifies a previously unknown mechanism by which GLED can improve pain management. Clinical translation of these results will advance the development of an innovative therapy devoid of adverse effects. PERSPECTIVE: Development of new pain management therapies, especially for HIV patients, is crucial as long-term opioid prescription is not recommended due to adverse side effects. Green light addresses this necessity. Characterizing the underlying mechanisms of this potentially groundbreaking and safe antinociceptive therapy will advance its clinical translation.

Photobiomodulation associated to cellular therapy improve wound healing of experimental full thickness burn wounds in rats

Adipose derived stromal vascular fraction (SVF) is a method of cell therapy potentially applicable for treatment of full thickness burns. Here we investigated if the association of photobiomodulation (PBM) with SVF therapy could improve wound healing in experimentally induced full thickness burn wounds in rats compared to the topical agent 2% silver sulfadiazine in a dose-dependent manner. Sixty-six male Wistar rats were divided in 4 groups containing 5 animals each which received the following treatments: 2% sulfadiazine (SD), SVF, SVF plus PBM at 30 mW (SVFL30), and SVF plus PBM at 100 mW (SVFL100). Two donor animals were used for each experimental series with 3, 7 and 30 days. Digital photography, microscopic analysis with Hematoxilin and Eosin (H&E), quantification of collagen type I by picrosirius red staining analysis and wound contraction evaluation were performed in order to quantify the results. At day 3 SVF alone or combined with PBM promoted increased early inflammatory response compared to SD. At day 7 SVFL30 and SVFL100 enhanced inflammatory cells infiltration, angiogenesis and fibroblast content compared to SVF and SD groups. At day 30 collagen concentration and wound contraction were higher in SVFL30 when compared to the other groups. In conclusion PBM promotes a synergistic outcome with SVF therapy with a dose dependent effect potentializing wound healing of experimental full thickness burns in rats through amplification of early inflammatory response, enhanced angiogenesis, fibroblast content, accentuated wound contraction and collagen concentration.