title: Low-power laser therapy for carpal tunnel syndrome: effective optical power.
abstract: Low-power laser therapy has been used for the non-surgical treatment of mild to moderate carpal tunnel syndrome, although its efficacy has been a long-standing controversy. The laser parameters in low-power laser therapy are closely related to the laser effect on human tissue. To evaluate the efficacy of low-power laser therapy, laser parameters should be accurately measured and controlled, which has been ignored in previous clinical trials. Here, we report the measurement of the effective optical power of low-power laser therapy for carpal tunnel syndrome. By monitoring the backside reflection and scattering laser power from human skin at the wrist, the effective laser power can be inferred. Using clinical measurements from 30 cases, we found that the effective laser power differed significantly among cases, with the measured laser reflection coefficient ranging from 1.8% to 54%. The reflection coefficient for 36.7% of these 30 cases was in the range of 10-20%, but for 16.7% of cases, it was higher than 40%. Consequently, monitoring the effective optical power during laser irradiation is necessary for the laser therapy of carpal tunnel syndrome.
authors.affiliation: Department of Neurology, Tongji Hospital, Tongji University School of Medicine, Shanghai, China.
authors.forename: Yan
authors.identifier: 0000-0002-0999-0819
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai, China.
authors.forename: Cheng-Qiang
authors.initials: CQ
authors.lastname: Zhao
authors.affiliation: Department of Rehabilitation Medicine, Tongji Hospital, Tongji University School of Medicine, Shanghai, China.
authors.forename: Gang
authors.initials: G
authors.lastname: Ye
authors.affiliation: Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai, China.
authors.forename: Can-Dong
authors.initials: CD
authors.lastname: Liu
authors.affiliation: Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai, China.
authors.forename: Wen-Dong
authors.initials: WD
authors.lastname: Xu
keywords: carpal tunnel syndrome; diode laser; laser power measurement; laser therapy; median nerve; nerve regeneration; neural regeneration; peripheral nerve regeneration; skin absorption; skin reflection; skin scattering