Different Treatment Paradigms of 830 nm Photobiomodulation are Retinoprotective in a Rodent Model of Retinitis Pigmentosa

Abstract

Purpose: Previous studies in our laboratory have shown that 830 nm photobiomodulaton (PBM) protects against retinal dysfunction and photoreceptor cell death in the P23H rat model of retinitis pigmentosa when administered early in the course of the disease. The purpose of the present study was to determine if 830 nm PBM would continue to protect against retinal dysfunction and photoreceptor cell death as the animals matured.

Methods: All studies were conducted in compliance with the ARVO Statement for the Use of Animals in Ophthalmic and Visual Research. P23H [Line 1] rats were treated once per day with 830 nm light (180 s; 25 mW/cm2; 4.5 J/cm2) using a light-emitting diode array (QDI, Barneveld WI) from [1] postnatal day p10 to p25, [2] p10 to p40 or [3] p20 to p40. Sham-treated rats were restrained for 180 seconds, but not exposed to 830 nm light. Retinal stucture and function was assessed at p30 or p45 by measuring photoreceptor function with electroretinography (ERG), and retinal morphology using spectral domain optical coherence tomography (SD-OCT).

Results: 830nm PBM preserved retinal function and retinal morphology in 830 nm light-treated animals in comparison to the sham-treated group in each treatment protocol. Scotopic full-field flash ERG responses over a range of flash intensities (from 10 to 25000 mcd.s/m2) were greater in 830 nm light-treated P23H rats compared to sham-treated P23H rats. SD-OCT imaging showed that 830 nm PBM also preserved the structural integrity of the retina in each treatment protocol.

Conclusions: Our findings confirm that the retinoprotective effects of 830 PBM observed early in the course of retinal degeneration in the P23H rat persist as the animals mature. Based on our findings and on other studies documenting the neuroprotective actions of PBM in experimental and clinical studies, we propose that photobiomodulation is an innovative, non-invasive therapeutic approach for the treatment of retinal degenerative disease.

Keywords: 695 retinal degenerations: cell biology • 600 mitochondria • 648 photoreceptors