title: Safety assessment of trans-tympanic photobiomodulation.
abstract: We evaluated functional and morphological changes after trans-tympanic laser application using several different powers of photobiomodulation (PBM). The left (L) ears of 17 rats were irradiated for 30 min daily over 14 days using a power density of 909.1 (group A, 5040 J), 1136.4 (group B, 6300 J), and 1363.6 (group C, 7560 J) mW/cm(2). The right (N) ears served as controls. The safety of PBM was determined by endoscopic findings, auditory brainstem response (ABR) thresholds, and histological images of hair cells using confocal microscopy, and light microscopic images of the external auditory canal (EAC) and tympanic membrane (TM). Endoscopic findings revealed severe inflammation in the TM of C group; no other group showed damage in the TM. No significant difference in ABR threshold was found in the PBM-treated groups (excluding the group with TM damage). Confocal microscopy showed no histological difference between the AL and AN, or BL and BN groups. However, light microscopy showed more prominent edema, inflammation, and vascular congestion in the TM of BL ears. This study found a dose-response relationship between laser power parameters and TM changes. These results will be useful for defining future allowance criteria for trans-tympanic laser therapies.
authors.affiliation: Department of Otolaryngology-Head & Neck Surgery, Cheong-Ju Saint Mary's Hospital, Cheong-Ju, South Korea.|Department of Medical Laser Graduate School of Medicine, Dankook University, Juk-Jeon, South Korea.
authors.forename: Tae-Hyun
authors.initials: TH
authors.lastname: Moon
authors.affiliation: Department of Medical Laser Graduate School of Medicine, Dankook University, Juk-Jeon, South Korea.|KRESGE Hearing Research Institute, University of Michigan, Ann Arbor, MI, USA.
authors.forename: Min Young
authors.initials: MY
authors.lastname: Lee
authors.affiliation: Department of Otolaryngology-Head & Neck Surgery, College of Medicine, Dankook University, Cheonan, South Korea.
authors.forename: Jae Yun
authors.initials: JY
authors.lastname: Jung
authors.affiliation: Beckman Laser Institute-Korea, College of Medicine, Dankook University, Cheonan, South Korea.|Department of Biomedical Science, Biomedical Translational Research Institute, Dankook University, Cheonan, Chungnam, South Korea.
authors.forename: Jin-Chul
authors.initials: JC
authors.lastname: Ahn
authors.affiliation: Beckman Laser Institute-Korea, College of Medicine, Dankook University, Cheonan, South Korea.
authors.forename: So-Young
authors.initials: SY
authors.lastname: Chang
authors.affiliation: Department of Otolaryngology-Head & Neck Surgery, College of Medicine, Dankook University, Cheonan, South Korea.|Beckman Laser Institute-Korea, College of Medicine, Dankook University, Cheonan, South Korea.
authors.forename: Phil-Sang
authors.initials: PS
authors.lastname: Chung
authors.affiliation: Department of Otolaryngology-Head & Neck Surgery, College of Medicine, Dankook University, Cheonan, South Korea.
authors.forename: Chung-Ku
authors.initials: CK
authors.lastname: Rhee
authors.affiliation: Department of Otolaryngology-Head & Neck Surgery, Cheong-Ju Saint Mary's Hospital, Cheong-Ju, South Korea.
authors.forename: Yoon-Hwan
authors.initials: YH
authors.lastname: Kim
authors.affiliation: Department of Otorhinolaryngology-Head & Neck Surgery, Seoul National University Hospital, Seoul, 110-744, South Korea. drmung@naver.com.
authors.forename: Myung-Whan
authors.initials: MW
authors.lastname: Suh
mesh_terms: D000818:Animals; D004424:Ear Canal / Q000502:physiology / Q000528:radiation effects; D016057:Evoked Potentials, Auditory, Brain Stem / Q000528:radiation effects; D028022:Low-Level Light Therapy / Q000009:adverse effects*; D008297:Male; D051381:Rats; D012449:Safety; D014432:Tympanic Membrane / Q000502:physiology / Q000528:radiation effects*
keywords: Cochlea; Laser therapy; Safety