Light in the red and near-infrared ends of the spectrum accelerate healing in all cells and tissues. One of the ways they accomplish this is by acting as potent antioxidants. They also inhibits nitric oxide production.
The potential of red and near-infrared light in the prevention or reversal of hearing loss has been a subject of considerable interest in recent research.In a 2016 study, researchers investigated the effects of near-infrared light on auditory cells in vitro, prior to subjecting them to oxidative stress by exposing them to various toxins. The results of this study indicated that the application of near-infrared light prior to treatment with chemotherapy drugs and endotoxins led to alterations in mitochondrial metabolism and oxidative stress response for a duration of up to 24 hours following treatment.
The study authors concluded that their findings demonstrate a reduction in inflammatory cytokines and stress levels resulting from NIR applied to HEI-OC1 auditory cells prior to treatment with gentamicin or lipopolysaccharide.The results of the study indicated that pre-treatment with near-infrared light led to a decrease in pro-inflammatory markers associated with increased reactive oxygen species and nitric oxide.
The application of near-infrared light prior to chemical insults has been demonstrated to impede the release of factors that precipitate hearing loss. Furthermore, the administration of near-infrared light has been shown to facilitate the recovery of hearing thresholds following acute acoustic trauma.
Study #1: Can Red Light Reverse Hearing Loss?The present study sought to evaluate the effect of near-infrared light on hearing loss following chemotherapy poisoning. Hearing was assessed following gentamicin administration and again after 10 days of light therapy.Scanning electron microscopic images revealed that “LLLT significantly increased the number of hair cells in middle and basal turns. Hearing was significantly improved by laser irradiation. After LLLT treatment, both the hearing threshold and hair-cell count significantly improved.”
These results suggest that near-infrared light administered after chemical poisoning can promote the regrowth of cochlear hair cells and restore hearing in mice.Study #2: Can Red Light Reverse Hearing Loss?In this study, rats were exposed to intense noise in both ears. Afterwards, their right ears were irradiated with near-infrared light for 30-minute treatments daily for five days.
The auditory brainstem response was measured to assess auditory function recovery, revealing accelerated recovery in the LLLT-treated groups compared to the non-treatment group on days 2, 4, 7, Und 14 after noise exposure.Morphological observations further revealed a significantly higher outer hair cell survival rate in the LLLT groups.
Researchers sought indicators of oxidative stress and apoptosis in untreated versus treated cells and found “strong immunoreactivities in the inner ear tissues of the non-treatment group, whereas these signals decreased in the LLLT group at 165mW/cm(2) power density.”
