The effects of photobiomodulation on animal model with retinopathy of prematurity

Abstract

Retinopathy of Prematurity (ROP) is a sight-threatening disease that can affect up to 68% of preterm infants. ROP has a biphasic disease process characterized by hyperoxia-induced vasoobliteration followed by hypoxia-induced neovascularization. Conventional treatment involves avascular retinal ablation by laser photocoagulation, but it is invasive and can cause visual field reduction. Intravitreal injection of an anti-vascular endothelial growth factor (VEGF) agent is an effective treatment for ROP. However, its use alone does not lower the risk of retinal detachment or recurrence of ROP. Thus, this study explored the potential of photobiomodulation (PBM), a non-invasive therapy that utilized near-infrared light, on preventing ROP in animal model with oxygen-induced retinopathy (OIR). It has been suggested in previous studies that cytochrome c oxidase (COX) in mitochondria acted as the primary photo-acceptors of PBM, and its stimulation initiated a cascade of signaling events that eventually resulted in a reduction in oxidative stress, inflammatory markers, and improvement in cell survival. This study showed that PBM was effective in reducing vaso-obliteration and neovascularization, the two hallmark features of ROP, in OIR mice(P<0.05), on postnatal day 12 and day 17 respectively. Histological analysis showed that there was a general increasing trend of thickness in total, GCL, INL and ONL in both central and mid-peripheral retinal zones observed in P17 mice with OIR after PBM, but none of them reached statistical significance. TUNEL staining for quantifying cell deaths showed significantly fewer cell deaths in INL layer on P17 OIR mice after PBM treatment ((P<0.05). Electroretinogram assessment showed an increasing trend in the a-wave and b-wave amplitude on P17 OIR mice after PBM, but the results were not statistically significant. The findings suggested that PBM might be an effective and safe treatment for ROP. However, only some of the results were statistically significant and more studies are needed to draw a conclusion on the effects of PBM on histological and functional aspect of ROP.