A new perspective on delivery of red-near-infrared light therapy for disorders of the brain
MetadataShow full item record
Red-near-infrared light has been used for a range of therapeutic purposes. However, clinical trials of near-infrared laser light for treatment of stroke were abandoned after failing interim futility analyses. Lack of efficacy has been attributed to sub-optimal treatment parameters and low penetrance of light to affected brain regions. Here, we assess penetrance of wavelengths from 450-880 nm in human post-mortem samples, and demonstrate that human skin, skull bone and brain transmits therapeutically relevant quantities of light from external sources at wavelengths above 600 nm. Transmission through post-mortem skull bone was dependent upon thickness, and ranged from 5-12% at peak wavelengths of 700-850 nm. Transmission through brain tissue ranged from 1-7%, following an approximately linear relationship between absorbance and tissue thickness. Importantly, natural sunlight encompasses the wavelengths used in red-near-infrared light therapy. Calculations of the average irradiance of light delivered by sunlight demonstrate that sunlight can provide doses of light equivalent to - and in some cases greater than - those used in therapeutic trials. Natural sunlight could, therefore, be used as a source of therapeutic red-near-infrared light, but equally its contribution must be considered when assessing and controlling therapeutic dose in patients. For targets deep within the brain, it is unlikely that sufficient doses of light can be delivered trans-cranially; therapeutic light must be supplied via optical fibers or implanted light sources.
Showing items related by title, author, creator and subject.
Method for the assessment of effects of a range of wavelengths and intensities of red/near-infrared light therapy on oxidative stress in vitroGiacci, M.; Hart, N.; Hartz, R.; Harvey, A.; Hodgetts, S.; Fitzgerald, Melinda (2015)Red/near-infrared light therapy (R/NIR-LT), delivered by laser or light emitting diode (LED), improves functional and morphological outcomes in a range of central nervous system injuries in vivo, possibly by reducing ...
Differential effects of 670 and 830 nm red near infrared irradiation therapy: A comparative study of optic nerve injury, retinal degeneration, traumatic brain and spinal cord injuryGiacci, M.; Wheeler, L.; Lovett, S.; Dishington, E.; Majda, B.; Bartlett, C.; Thornton, E.; Harford-Wright, E.; Leonard, A.; Vink, R.; Harvey, A.; Provis, J.; Dunlop, S.; Hart, N.; Hodgetts, S.; Natoli, R.; Van Den Heuvel, C.; Fitzgerald, Melinda (2014)Red/near-infrared irradiation therapy (R/NIR-IT) delivered by laser or light-emitting diode (LED) has improved functional outcomes in a range of CNS injuries. However, translation of R/NIR-IT to the clinic for treatment ...
Comparative assessment of phototherapy protocols for reduction of oxidative stress in partially transected spinal cord slices undergoing secondary degenerationAshworth, B.; Stephens, E.; Bartlett, C.; Serghiou, S.; Giacci, M.; Williams, A.; Hart, N.; Fitzgerald, Melinda (2016)Background: Red/near-infrared light therapy (R/NIR-LT) has been developed as a treatment for a range of conditions, including injury to the central nervous system (CNS). However, clinical trials have reported variable or ...