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Results for “Low-Level Light Therapy”

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PubMed2026

Repeated low-level red-light therapy for improving asthenopic symptoms and accommodation in presbyopia.

BACKGROUND: To assess the short-term effectiveness of repeated low-level red light (RLRL) therapy in relieving asthenopia and enhancing accommodation in presbyopia. METHODS: This randomized, parallel-group, double-masked clinical trial enrolled adults with presbyopia and self-reported asthenopia. Participants were allocated using computer-generated randomization and randomly assigned at a 1:1 ratio to RLRL or sham groups. Blinding included participants, examiners, assessors, and statisticians. The primary outcome was the change from baseline in the Computer Vision Syndrome Questionnaire (CVS-Q) score at day 31. Secondary outcomes were the change in accommodative amplitude (AA), Near Activity Visual Questionnaire (NAVQ) score, habitual near visual acuity, near-addition power, accommodative facility, positive and negative relative accommodation, binocular cross-cylinder response, and accommodative convergence-to-accommodation ratio. Continuous outcomes were analyzed using linear mixed-effects models. RESULTS: Sixty-four of 66 randomized participants (aged 41-62 years) completed the 1-month trial. At day 31, RLRL showed greater improvement than sham in CVS-Q score (adjusted mean difference, -1.75 points; 95% CI, -3.10 to -0.39), binocular AA (1.09 D; 95% CI, 0.37 to 1.82), and NAVQ score (-8.07 points; 95% CI, -14.17 to -1.97). The effect on AA was most pronounced in a subgroup of eyes with baseline amplitude >2.0 D (adjusted mean difference 1.33 D; 95% CI 0.32-2.34). Other measures did not differ between groups at each visit. No treatment-related adverse events were reported. Adherence was similar between groups (mean compliance: 98.2% vs 97.5%). CONCLUSIONS: Short-term treatment with RLRL significantly reduced asthenopic symptoms and improved accommodative amplitude in individuals with presbyopia.Trial registration: NCT06745661 (registered December 8, 2024).

Humans↗

PubMed2026

Photobiomodulation as an Adjunct to Resistance Training in Older Adults: A Systematic Review and Meta-Analysis.

BACKGROUND: Photobiomodulation (PBM) has been proposed as an adjunct to resistance training to enhance strength adaptations; however, findings from randomized controlled trials (RCTs) remain inconsistent. This study aimed to evaluate whether adjunctive PBM improves maximal strength gains when combined with periodized resistance training in older adults. METHODS: RCTs were identified through systematic searches of PubMed, Scopus, Embase, PEDro, Web of Science, the Cochrane Library, and CNKI from inception to January 2026. Eligible studies examined PBM delivered via low-level laser therapy or light-emitting diodes in combination with resistance training or other strength-oriented loading tasks. Prespecified meta-analyses were restricted to trials combining PBM with periodized resistance training that reported one-repetition maximum (1RM) outcomes; other studies were included in a narrative synthesis. RESULTS: Eleven RCTs (n = 456) were included. Five trials (PBM plus resistance training: n = 74; control: n = 72) met the criteria for meta-analysis. PBM combined with resistance training did not significantly improve maximal muscle strength compared with sham PBM (SMD = 0.26, 95% CI -0.08 to 0.59; p = 0.14; I2 = 4%). Subgroup analyses showed a nonsignificant trend favoring PBM for unilateral 1RM, with no effect for bilateral outcomes and no significant subgroup differences. Sensitivity analyses indicated that the unilateral effect was dependent on individual studies. In nonresistance training contexts, some studies reported potential benefits for fatigue-, recovery-, or function-related outcomes, particularly in frail or critically ill older adults, although findings were inconsistent. CONCLUSION: Current evidence does not demonstrate a clear additional benefit of PBM on maximal strength when combined with resistance training in older adults, although a small effect cannot be excluded. PBM may have selective value in improving recovery-related outcomes and supporting training tolerance in vulnerable populations. Larger, well-designed RCTs are needed to clarify its role.

Humans↗

PubMed2026

Effect of photobiomodulation on pain relief and functional improvement in fractures: a systematic review and meta-analysis.

INTRODUCTION: Fractures, the most common type of trauma, can cause considerable distress to patients. Pain can not only affect the comfort of fracture patients but also delay their participation in rehabilitation training. Photobiomodulation (PBM) has been associated with pain reduction and the promotion of tissue healing. This systematic review and meta-analysis aimed to evaluate the efficacy of PBM in reducing pain and promoting rehabilitation in patients with fractures. METHODS: This study was registered on PROSPERO (CRD42024591373). We systematically searched PubMed, EMBASE, the Cochrane Library and Web of Science for RCTs that investigated PBM in fractures as of August 2025. The primary outcome was the pain score. The secondary outcomes included functional and healing. RESULT: Finally, 12 and 9 studies were ultimately included in the systematic review and meta-analysis, respectively. The pooled analysis showed that the one-week pain score was lower in the PBM group than in the placebo group (MD -0.74, 95% CI -1.00, -0.47, p < 0.0001, I2 = 0%). Subgroup analysis showed that the difference between the two groups was statistically significant regardless of fracture site or acupoint irradiation. Changes in pain scores were statistically significant in both groups at different wavelength combinations. The improvement in grip strength at 4 weeks was significantly greater in PBM than in placebo (MD 5.03, 95% CI 4.29, 5.78; p < 0.0001; I2 = 0%). There were no significant differences in pain and functional scores at 4-26 weeks. Bone healing did not show differences between the two groups. No side effects reported. CONCLUSION: PBM appears to relieve short-term pain in fractures and improve grip strength in patients with upper limb fractures, but does not show significant long-term benefits. Evidence for mandibular functional recovery and bone healing remains inconsistent. Future studies should determine therapeutic parameters and their impact on bone healing and long-term functional outcomes across fracture types.

Humans↗

PubMed2026

Systematic Review on the Effectiveness of Photobiomodulation Therapy on Enhancing Musculoskeletal Rehabilitation Outcomes after Total Knee and Hip Arthroplasty.

BACKGROUND: Total knee and hip arthroplasty (TKA/THA) effectively alleviate chronic pain and improve joint function and quality of life. However, postoperative recovery is often hindered by pain, edema, restricted range of motion (ROM), and muscle weakness, necessitating structured physical rehabilitation. Photobiomodulation Therapy (PBMT) has been proposed as an adjunct modality to enhance rehabilitation outcomes. This systematic review evaluates the efficacy of PBMT in reducing postoperative pain and edema as well as improving ROM and functional performance compared with placebo or standard physical therapy in post-arthroplasty patients. METHODS: A systematic search of PubMed, ProQuest, ScienceDirect, and Google Scholar was conducted from inception to May 31, 2025. Only prospective controlled trials assessing PBMT effects on postoperative pain, swelling, ROM, or functional performance following TKA or THA were included. Case reports, uncontrolled studies, and trials focusing on unrelated outcomes were excluded. Article selection involved title, abstract, and full-text screening, with additional studies identified through reference lists. The review is registered in PROSPERO (CRD420251123169). RESULTS: Four randomized controlled trials (RCTs; n = 133 participants) met the inclusion criteria, three studies focused on TKA, and one study examined THA. PBMT significantly improved postoperative pain and edema reduction in three trials, while two studies demonstrated enhanced ROM and functional outcomes compared with control or placebo interventions. PEDro scores ranged from 8 to 10, indicating moderate-to-high methodological quality. CONCLUSIONS: PBMT shows promising short-term benefits in reducing postoperative pain and swelling and improving functional performance after knee or hip arthroplasty. However, due to heterogeneity in treatment parameters and limited high-quality trials, conclusive evidence remains insufficient. Future large-scale RCTs with standardized PBMT parameters and extended follow-up are warranted to confirm its clinical efficacy.

Humans↗

PubMed2026

Effects of Photobiomodulation Therapy in Lateral Luxation of Anterior Permanent Teeth: A Randomized, Double-Blind Clinical Trial.

BACKGROUND: Among the traumatic dental injuries (TDIs), lateral luxation may present poor prognosis due to frequent root resorption and consequent tooth loss. Photobiomodulation therapy (PBMT) modulates cellular activities (proliferation, differentiation, growth factor secretion) and may improve outcomes. OBJECTIVE: This randomized, double-blind, placebo-controlled trial evaluated PBMT (660 vs. 808 nm) for post-operative pain and pulp sensitivity recovery in lateral luxation of permanent anterior teeth. METHODS: Initially, 41 patients were included, with a total of 63 teeth traumatized by lateral luxation and were allocated to G1 (n = 21): Splinting + sham PBM (placebo), G2 (n = 21): Splinting + 808 nm infrared PBM and G3 (n = 21): Splinting + 660 nm red PBM. Four weekly sessions (3 J/point, 3 points) were administered. Pain (by numeric rating scale) and pulp sensitivity (by cold test) were assessed weekly. Pain was analyzed using the Kruskal-Wallis test, followed by multiple comparisons using Dunn's method with Bonferroni correction, and pulp sensitivity by a logistic regression model (p < 0.05). RESULTS: Three participants (total of 5 teeth) were excluded due to loss to follow-up. Fifty-eight teeth were analyzed (G1 = 21, G2 = 17, G3 = 20). Pain: All groups showed a significant reduction in pain over time (p < 0.001). Both G2 and G3 demonstrated a significantly greater reduction in pain compared to G1 (p < 0.001 and p = 0.026, respectively). No significant difference in pain reduction was observed between G2 and G3. Pulp sensitivity: G2 showed a significant improvement over time (p < 0.001), despite starting from a more unfavorable baseline. In contrast, no significant change in pulp sensitivity was observed for G1 or G3 between the initial and final assessments. CONCLUSION: Within the limitations of this clinical study, all intervention groups were effective in reducing pain in lateral luxation of permanent anterior teeth, with superior results for laser groups compared to the placebo. However, only the 808 nm laser irradiation protocol demonstrated a significant improvement in pulp sensitivity, suggesting it may offer a more complete therapeutic response.

Humans↗

PubMed2026

Comparison of a 755-nm picosecond laser and a 1565-nm nonablative fractional laser for the treatment of atrophic acne scars: a 20-week prospective, randomized, split-face clinical study.

To compare the efficacy and safety of a 755-nm picosecond laser with a diffractive lens array (P-DLA) and a 1565-nm nonablative fractional laser (NAFL) for the treatment of atrophic acne scars. Twenty-seven patients with atrophic acne scars underwent three sessions of randomized split-face treatment with P-DLA and NAFL at 4-week intervals. Patients were followed up at 1, 2, and 3 months after the final treatment. Efficacy was assessed using the Échelle d'Évaluation Clinique des Cicatrices d'Acné (ECCA) grading scale, the Investigator's Global Assessment (IGA) score, patients' self-rated improvement, and overall satisfaction. Treatment-related adverse reactions were recorded daily by patients until resolution. Both modalities demonstrated significant improvements in scar appearance based on ECCA score, IGA score, and patients' self-rated improvement (P < 0.001). No statistically significant differences in efficacy were observed between the two treatments. However, the P-DLA group showed higher patient satisfaction (P = 0.035) and a more favorable safety profile, including shorter durations of erythema and edema and the absence of crusting. Both P-DLA and NAFL were effective and safe for the treatment of atrophic acne scars, with similar efficacy. P-DLA offered better tolerability.

Humans↗

PubMed2026

Photothermal-Activated Platelet-Rich Plasma Versus Conventional Platelet-Rich Plasma for Melasma: A Split-Face, Double-Blind Randomized Controlled Trial.

BACKGROUND: Melasma is a common acquired pigmentary disorder that predominantly affects women with darker skin types and substantially impairs quality of life. Current treatments are limited by variable efficacy, adverse effects, and frequent recurrence. Platelet-rich plasma (PRP) has emerged as a potential regenerative treatment through growth-factor-mediated modulation of melanogenesis. Photothermal activation, which combines photobiomodulation with controlled hypothermic conditioning, has been hypothesized to promote a more sustained growth-factor release than conventional PRP. This study compared the efficacy and safety of photothermal-activated PRP (PT-PRP) and conventional PRP (C-PRP) for melasma treatment. METHODS: This split-face, double-blind, randomized controlled trial included 26 women with epidermal or mixed-type melasma. Each participant received three monthly sessions of intradermal PRP, with PT-PRP and C-PRP injected into opposite facial sides. Outcomes were assessed at weeks 0, 4, 8, and 12 using the modified Melasma Area and Severity Index (mMASI), Mexameter melanin and erythema indices, patient satisfaction, overall improvement, and adverse events. RESULTS: Both treatments significantly reduced mMASI by week 12, with no significant between-group differences at any time point. C-PRP showed significant mMASI improvement from week 4, whereas PT-PRP reached significance from week 8. For the melanin index, PT-PRP produced a significant within-group reduction at week 12, while C-PRP did not. At week 12, PT-PRP showed a significantly lower melanin index than C-PRP. Mild injection-site bruising was the only adverse event. CONCLUSION: PT-PRP and C-PRP produced comparable clinical improvement, but PT-PRP achieved greater objective melanin reduction at week 12. PT-PRP may represent a safe alternative treatment for melasma. TRIAL REGISTRATION: Thai Clinical Trials Registry: TCTR20260318004.

Humans↗

PubMed2026

Transcranial Photobiomodulation Variables Assessment Battery: Development and Validation.

Transcranial photobiomodulation (tPBM) response variability is partly driven by biophysical characteristics such as skin tone and hair properties that attenuate photon penetration, and by lifestyle factors including sleep quality, alcohol use, and nicotine consumption that disrupt the mitochondrial and vascular pathways on which tPBM acts. To date, no validated self-report tool exists to capture these moderators systematically. To address this gap, the tPBM Variables Assessment Battery was developed and psychometrically evaluated. It integrates adapted versions of established measures (Brief Pittsburgh Sleep Quality Index, E-cigarette Dependence Scale, Hair Scale Assessment PRO, Monk Skin Tone Scale, and Heaviness of Smoking Index), validated wellbeing evaluators (Ryff's Psychological Wellbeing), and custom measures (Hairstyle Classification, Hair Color Classification). Face and content validity met recommended expert thresholds, internal consistency was acceptable across adapted subscales, and criterion validity analyses confirmed meaningful associations between the lifestyle components and PROMIS-10 global health outcomes. The battery is low-burden, digitally deployable, and psychometrically defensible, offering a practical tool for characterizing the variables most likely to moderate tPBM response in home-use studies.

Humans↗

PubMed1992

Effects of visible and near-infrared lasers on cell cultures.

The effect of 360, 632 and 780 nm light on NIH fibroblast cells was examined. Mitosis counts of irradiated cells at various energy doses were taken. Scanning electron micrographs of these cells were studied. It is suggested that low-level laser therapy in the visible and in the near-infrared region is due to cell respiration stimulation by either the endogenous porphyrins in the cell, or by the cytochromes.

3T3 Cells↗

PubMed1989

Photodynamic therapy of human choriocarcinoma transplanted to the hamster cheek pouch. II. Intra-lesional photosensitization.

Photodynamic therapy (PDT) uses light-activated compounds, such as hematoporphyrins, to produce cytotoxic effects after illumination. Human choriocarcinoma cells were transplanted into the hamster cheek pouch to study PDT. The transplanted choriocarcinoma secretes human chorionic gonadotropin (hCG) in proportion to tumor volume. Red light (630 nm) from an argon-pumped dye laser (100-200 J/cm2) was used to illuminate tumors sensitized with dihematoporphyrin ether (DHE). Previous work has demonstrated complete regression (CR) of 90% of tumors (18/20) after one or two PDT sessions, while contralateral cheek pouch tumors continued to grow despite intraperitoneal DHE. Neither DHE nor laser light alone resulted in significant CRs. In this study we evaluated intratumoral injection of DHE followed in 2 hr by laser treatment. In all tumors, localization of DHE was demonstrated by induced fluorescence with ultraviolet light or He:Cd laser. After a single treatment, 14 of 38 tumors (37%) completely regressed (hCG less than mIU/ml); 4 tumors regressed grossly with low-level hCG [partial regression (PR)]. After repeat treatment there were 10 additional CRs in 19 rapidly enlarging tumors. After a third treatment 3 CRs and 3 PRs were achieved in 6 tumors. Because of large volumes, 2 of 3 progressing tumors failed to fluoresce uniformly after intratumoral DHE and were treated after intraperitoneal DHE injection; both completely responded. Overall, 29 of 38 tumors (76%) completely responded to PDT, and 7 partially responded (18%) with no gross tumor remaining in 5 of the 7. Only 5% of tumors (2/38) were non-responders. Photodynamic therapy results in gross elimination of 90% of tumors (52/58) in this model after intraperitoneal or intratumoral DHE sensitization (P less than 0.0001). DHE in chorio-carcinomas is easily detected and may enable detection of occult foci of malignancy. Choriocarcinoma transplanted into the hamster cheek pouch is highly responsive to photodynamic therapy. Clinical trials of PDT in gynecologic cancers are warranted to confirm the high response rates observed in refractory nongynecologic cancers.

Animals↗

PubMed1992

Percutaneous delivery of low-level laser energy reverses histamine-induced spasm in atherosclerotic Yucatan microswine.

BACKGROUND: Previous in vitro experiments performed in our laboratory have shown that low-level laser energy may produce prompt reduction in isometric tension of vascular smooth muscle. The present study was designed to extend these previous in vitro findings to an in vivo model and thereby investigate the hypothesis that laser light delivered percutaneously in vivo could successfully reverse arterial spasm. METHODS AND RESULTS: Spasm defined as greater than 50% reversible reduction in luminal diameter persisting for greater than or equal to 5 minutes was successfully provoked by injection of histamine (100-400 micrograms/kg) in 13 arteries among 10 atherosclerotic Yucatan microswine; the magnitude of histamine-induced vasoconstriction was then documented angiographically by repeated injections of contrast media for as long as 30 minutes (controls). After return of angiographic luminal diameter to baseline, spasm was reproduced with a second injection of histamine into the same artery. Representative wavelengths generated by ultraviolet (UV), visible, and infrared lasers were then delivered percutaneously via conventional fiberoptics to the site of spasm, and angiographic assessment was repeated for as long as 30 minutes (treatment trial). In three arteries treated with UV (351 nm) light from an excimer laser, angiographic luminal diameter narrowing decreased from 100% to 23.9%, 50.0% to 9.3%, and 76.0% to 42.3%, respectively. The magnitude of laser-induced increase in luminal diameter was 50.2 +/- 22.7%, which was significantly greater than the magnitude of relaxation observed spontaneously during the control trials (10.9 +/- 9.8%, p = 0.02). Visible light from a helium-neon (632 nm) laser accomplished complete reversal of histamine-induced spasm in two of four arteries; in the remaining two arteries, luminal diameter narrowing percentages were reduced from 57.0% to 20.0% and from 76.5% to 30.8%, respectively. The magnitude of helium-neon laser-induced relaxation (55.8 +/- 17.9%) was again significantly greater than that observed during the control trials (0.9 +/- 1.9%, p = 0.01). Finally, infrared irradiation from a diode-pumped neodymium:yttrium aluminum garnet (1,064 nm) laser decreased histamine-induced luminal diameter narrowing in three arteries from 100% to 21.4%, 56.0% to 8.7%, and 68.3% to 35.3%, respectively. The magnitude of infrared laser-induced improvement in luminal diameter narrowing was 53.0 +/- 23.3%, which was significantly greater than that observed during the control trials (12.9 +/- 10.7%, p = 0.01). In three additional arteries, fiberoptic sham trials (without laser irradiation) failed to produce relaxation of histamine-induced spasm. CONCLUSIONS: These findings document for the first time that light-induced relaxation of vascular smooth muscle, previously documented in vitro, may be reproduced in vivo.

Animals↗