How does RLT help?
Mitochondrial dysfunction and oxidative damage to the retina have been implicated in many forms of retinal injury and degeneration. Mitochondrial repair and attenuation of oxidative stress are critical to the long-term survival of the retina. Red light therapy has been shown to act on mitochondria-mediated signaling pathways to preserve mitochondrial function, attenuate oxidative stress, stimulate the production of cytoprotective factors and prevent neuronal death.
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Mitochondrial dysfunction and oxidative damage to the retina have been implicated in many forms of retinal injury and degeneration including methanol intoxication, light-induced retinal damage, age-related macular degeneration (AMD) and retinitis pigmentosa.
NIR photons penetrate the brain, retina and optic nerve and this treatment, commonly known as photobiomodulation (PBM) has documented eﬃcacy in the prevention and treatment of neurodegenerative diseases in experimental and clinical studies. Numerous studies have documented the therapeutic potential and mechanism(s) of action of PBM in the treatment and pathogenesis of retinal injury and disease.
According to the research, here are some ways the RLT can help mitigate eye damage and improve retinal health:
Light Induced Retinal Damage
Oxidative damage produced by photo-oxidation of the photoreceptor outer segments is widely accepted as the initiating event in light-induced retinal damage (LD). In addition to structural changes to the retina, there is the induction of an inﬂammatory state characterized by an invasion of the outer retina by activated microglia.
Several studies have shown that RLT is protective against light-induced retinal degeneration administered before, during or after exposure to LD protected photoreceptor function, which was seen by a reduction in photoreceptor cell death and inﬂammatory stress biomarkers in the retina.
Pretreatment with PBM proved to be most eﬀective against LD compared to treatment during or after LD. Research ﬁndings indicate the RLT pretreatment attenuates oxidative damage to photoreceptors and reduces inﬂammation, which may reduce the stimulation of the complement cascade, thus further protecting photoreceptors.
Age-related Macular Degeneration
Progression of age-related macular degeneration (
AMD) is characterized by accumulation of
membranous debris, lipofuscin, and extracellular material and complement deposition. The advanced late-stage dry form of AMD, which accounts for 80% to 90% of the cases, is characterized by retinal pigment epithelium (RPE) and outer retinal atrophy. (CNV) as a hallmark of respective disease. Contributing factors to RPE cell degeneration include mitochondrial dysfunction, oxidative stress, inﬂammation and genetic disposition.
Since both mitochondria's health and the inﬂammatory state are inﬂuenced by RLT, it stood to reason that red and NIR light could treat AMD.
According to scientiﬁc studies, brief exposure to RLT in the aged retina has been shown to increase mitochondrial membrane potential and reduce inﬂammation. RLT is eﬀective in reducing retinal inﬂammation likely by cytochrome c oxidase activation in mice with a genotype similar to that in 50 % of AMD patients, even when brief exposures are delivered via environmental lighting. The eﬃcacy in the current research supports current early stage clinical trials of RLT in AMD patients.
What does the research show?
“These ﬁndings show that subjects with dry AMD (age-related macular degeneration) in earlier stages of the disease are more likely to respond better to PBM compared to subjects with more advanced disease and extensive central tissue loss.” (1)
“LLLT given over a 2 week period led to an improvement in visual acuity in most patients with AMD. Unlike other therapeutic approaches, LLLT improved visual acuity in patients with AMD of every stage. This study of a case series shows that LLLT may be a novel therapeutic option for both early and advanced forms of AMD. This simple and highly eﬀective treatment improves visual acuity and may help to prevent loss of vision without adverse side eﬀects.” (2)
“This study demonstrated that 670nm PBM ameliorates the damaging eﬀects of bright, continuous light on the retina. Tx with 670nm light before, during, or even after exposure to bright white light led to a signiﬁcant reduction in photoreceptor cell death and prevented the severe disruption of the outer retina and the RPE.” (3)
“Present data suggest that treatment with red light can lead to significant protection of the retina from LD. This treatment has the potential to reduce the adverse effects of bright light exposure; moreover, this noninvasive therapeutic modality has considerable promise for the treatment of retinal degenerative disorders and ocular inflammatory disease conditions.” (4)
“Taken as a whole, these studies in experimental models of retinal and optic nerve injury and disease show that far-red and near-infrared RLT improves mitochondrial function, reduces oxidative stress and modulates inﬂammatory mediators, leading to decreased apoptosis and retinoprotection.” (5)
“Photobiomodulation treatment statistically improved clinical and anatomical outcomes with more robust benefits observed in subjects with earlier stages of dry age-related macular degeneration. Repeated RLT treatments are necessary to maintain benefits. These pilot findings support previous reports and suggest the utility of RLT as a safe and effective therapy in subjects with dry age-related macular degeneration.” (6)
“(Red light) LED treatment has an evident protective effect on retinal cells against light-induced damage, which may be an innovative and non-invasive therapeutic approach to prevent or to delay age-related macular degeneration.” (7)
“NIR photobiomodulation is protective against bright-light-induced retinal degeneration, even when NIR treatment is applied after exposure to light. This protective effect appears to involve a reduction of cell death and inflammation. Photobiomodulation has the potential to become an important treatment modality for the prevention or treatment of light-induced stress in the retina. More generally, it could be beneficial in the prevention and treatment of retinal conditions involving inflammatory mechanisms.” (8)
“(Regarding diabetic retinopathy) the treated eyes (using red light) of all patients demonstrated a statistically significant decrease in macular thickness by an average of 20%, while non-treated eyes featured a slight increase in thickness by 3% on average.” (9)
“Our study identified mitochondria related red light and near-infrared light-triggered defense mechanisms promoting photoreceptor neuroprotection. The observed improvement of mitochondrial and extramitochondrial respiration in both inner and outer segments is linked with reduced oxidative stress including its cellular consequences and reduced mitochondria-induced apoptosis.” (10)
“Treatment with red light before, during or even after exposure to blue light led to significant reduction in photoreceptor cell death and prevented the severe disruption of the outer retina and the RPE (retinal pigment epithelium). Photobiomodulation prevented the obliteration of the choroidal vascular network, thus assuring the maintenance of the blood-retina barrier… Photobiomodulation also reduced cell stress and inflammatory reaction in the retina.” (11)
**While the current scientific research seems to indicate many positive benefits of RLT in relation to fat loss, there is still an appreciable necessity for more extensive research to be conducted in this area, including double-blind RCT (randomized controlled trials), to provide a more comprehensive, robust overview that will further elucidate the optimal parameters and appropriate uses of RLT, which will ultimately lead the most safe and efficacious uses for eye health.