Aim: The LLLT was found to recover NIHL and ototoxicity induced hearing loss in rats but the optimal LLLT laser dosage to treat NIHL needs to be determined. The aim of this study was to find the optimal laser dosage to recover a NIHL with transmeatal-LLLT. Methods: Bilateral ears of rats were exposed to noise (narrow band noise, 120 dB, 16 kHz, 6 h). Left ears of the rats were irradiated with transmeatal-LLLT (830 nm) of 50, 100, 150, 200, 250, 300 mW for 60 minutes per day for 12 days, starting 1 day post induction of NIHL. Right ears were not irradiated and used as control ears. The hearing levels were measured at each frequency of 8, 12, and 32 kHz before the noise exposure, 1, 3, 8, and 12 days post noise exposure. The differences of hearing levels between left treated ear and right controlled ear at each frequency of different laser dosages (50 – 300 mW) were compared to see the most effective laser dosages to treat NIHL. Results: Hearing levels were most improved by 150 mW, slightly improved by 200 mW, not improved by 50 and 250 mW, and became worse by 300 mW. Conclusion: The results of this study suggest that most effective therapeutic laser dosage window to treat NIHL with transmeatal-LLLT was 150 mW for 12 days and it was not effective by 50, 250, and 300 mW.

Date Published: 26 February 2015
PDF: 6 pages
Proc. SPIE 9303, Photonic Therapeutics and Diagnostics XI, 93031M (26 February 2015); doi: 10.1117/12.2083044

Published in SPIE Proceedings Vol. 9303:
Photonic Therapeutics and Diagnostics XI
Hyun Wook Kang; Brian J. F. Wong M.D.; Melissa C. Skala; Bernard Choi; Guillermo J. Tearney M.D.; Andreas Mandelis; Nikiforos Kollias; Kenton W. Gregory M.D.; Mark W. Dewhirst D.V.M.; Justus F. Ilgner M.D.; Alfred Nuttal; Haishan Zeng; Laura Marcu; Claus-Peter Richter, Editor(s)