The effect of photobiomodulation on hearing loss: A systematic review.

OBJECTIVES: To assess outcomes associated with photobiomodulation therapy (PBMT) for hearing loss in human and animal studies. DESIGN: Systematic review and narrative synthesis in accordance with PRISMA guidelines. SETTING: Data bases searched: MEDLINE, EMBASE, CENTRAL, ClinicalTrials.gov and Web of Science. No limits were placed on language or year of publication. Review conducted in accordance with the PRISMA 2020 statement. PARTICIPANTS: All human and animal subjects treated with PBMT for hearing loss. MAIN OUTCOME MEASURES: Pre- and post-PBMT audio metric outcomes. RESULTS: Searches identified 122 abstracts and 49 full text articles. Of these, 17 studies met the inclusion criteria, reporting outcomes in 327 animals (11 studies), 30 humans (1 study), and 40 animal specimens (5 studies). PBMT parameters included 6 different wavelengths: 908 nm (1 study), 810 nm (1 study), 532 & 635 nm (1 study), 830 nm (3 studies), 808 nm (11 studies). The duration ranged from 4 to 60 minutes in a session, and the follow-up ranged from 5-28 days. Outcomes improved significantly when wavelengths within the range of 800-830 nm were used, and with greater duration of PBMT exposure. Included studies predominantly consisted of non-randomized controlled trials (10 studies). CONCLUSIONS: Hearing outcomes following PBMT appear to be superior to no PBMT for subjects with hearing loss, although higher level evidence is required to verify this. PBMT enables concentrated, focused delivery of light therapy to the inner ear through a non-invasive manner with minimal side effects. As a result of heterogeneity in reporting PBMT parameters and outcomes across the included studies, direct comparison is challenging.

The effect of photobiomodulation on tinnitus: a systematic review.

OBJECTIVE: To establish outcomes following photobiomodulation therapy for tinnitus in humans and animal studies. METHODS: A systematic review and narrative synthesis was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. The databases searched were: Medline, Embase, Cochrane Central Register of Controlled Trials ('Central'), ClinicalTrials.gov and Web of Science including the Web of Science Core collection. There were no limits on language or year of publication. RESULTS: The searches identified 194 abstracts and 61 full texts. Twenty-eight studies met the inclusion criteria, reporting outcomes in 1483 humans (26 studies) and 34 animals (2 studies). Photobiomodulation therapy parameters included 10 different wavelengths, and duration ranged from 9 seconds to 30 minutes per session. Follow up ranged from 7 days to 6 months. CONCLUSION: Tinnitus outcomes following photobiomodulation therapy are generally positive and superior to no photobiomodulation therapy; however, evidence of long-term therapeutic benefit is deficient. Photobiomodulation therapy enables concentrated, focused delivery of light therapy to the inner ear through a non-invasive manner, with minimal side effects.