title: Green laser light activates the inner ear.
abstract: The hearing performance with conventional hearing aids and cochlear implants is dramatically reduced in noisy environments and for sounds more complex than speech (e. g. music), partially due to the lack of localized sensorineural activation across different frequency regions with these devices. Laser light can be focused in a controlled manner and may provide more localized activation of the inner ear, the cochlea. We sought to assess whether visible light with parameters that could induce an optoacoustic effect (532 nm, 10-ns pulses) would activate the cochlea. Auditory brainstem responses (ABRs) were recorded preoperatively in anesthetized guinea pigs to confirm normal hearing. After opening the bulla, a 50-microm core-diameter optical fiber was positioned in the round window niche and directed toward the basilar membrane. Optically induced ABRs (OABRs), similar in shape to those of acoustic stimulation, were elicited with single pulses. The OABR peaks increased with energy level (0.6 to 23 microJ/pulse) and remained consistent even after 30 minutes of continuous stimulation at 13 microJ, indicating minimal or no stimulation-induced damage within the cochlea. Our findings demonstrate that visible light can effectively and reliably activate the cochlea without any apparent damage. Further studies are in progress to investigate the frequency-specific nature and mechanism of green light cochlear activation.
authors.affiliation: Medical University Hannover, Department of Otolaryngology, Carl-Neuberg-Strasse 1, Hannover, 30625, Germany. Wenzel.Gentiana@mh-hannover.de
authors.forename: Gentiana I
authors.initials: GI
authors.lastname: Wenzel
authors.forename: Sven
authors.initials: S
authors.lastname: Balster
authors.forename: Kaiyin
authors.initials: K
authors.lastname: Zhang
authors.forename: Hubert H
authors.initials: HH
authors.lastname: Lim
authors.forename: Uta
authors.initials: U
authors.lastname: Reich
authors.forename: Ole
authors.initials: O
authors.lastname: Massow
authors.forename: Holger
authors.initials: H
authors.lastname: Lubatschowski
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Ertmer
authors.forename: Thomas
authors.initials: T
authors.lastname: Lenarz
authors.forename: Guenter
authors.initials: G
authors.lastname: Reuter
mesh_terms: D000818:Animals; D003051:Cochlea / Q000502:physiology* / Q000528:radiation effects; D003116:Color; D004307:Dose-Response Relationship, Radiation; D016057:Evoked Potentials, Auditory, Brain Stem / Q000502:physiology* / Q000528:radiation effects; D006168:Guinea Pigs; D007834:Lasers; D010775:Photic Stimulation / Q000379:methods*; D011829:Radiation Dosage