NIR Photobiomodulation Does Not Alter Retinal Function or Morphology in Non-dystrophic Sprague Dawley Rats.

Abstract

Purpose: Previous studies in our laboratory have shown that 670nm and 830nm photobiomodulaton (PBM) protects against retinal dysfunction and photoreceptor cell death in rodent models of retinal injury and retinal degeneration. The purpose of this study was to test the hypothesis that NIR PBM would not alter retinal function or morphology in a non-dystrophic Sprague-Dawley rat.

Methods: All studies were conducted in compliance with the ARVO Statement for the Use of Animals in Ophthalmic and Visual Research. Sprague Dawley (Harlan Sprague-Dawley, Madison, WI) rats were treated once per day with either 670nm or 830nm light (180 s; 25 mW/cm2; 4.5 J/cm2) using a light-emitting diode array (QDI, Barneveld WI) from postnatal day p10 to p25. Sham-treated rats were restrained for 180 seconds, but not exposed to 670nm or 830nm light. Retinal function and structure were assessed at p30 by measuring photoreceptor function with electroretinography (ERG) and retinal morphology using spectral domain optical coherence tomography (SD-OCT).

Results: Photon irradiation with 670nm or 830 nm light did not alter ERG parameters in SD rats compared to sham-treated control animals. ERG a-wave amplitude and latency and ERG b-wave amplitude and latency were not altered by NIR PBM treatment. Retinal imaging studies using SD-OCT imaging revealed no differences in the structural integrity of the retina in NIR PBM treated rats compared to sham-treated control animals.

Conclusions: Our findings demonstrate the safety of 670nm and 830nm photobiomodulation applied to the retina in Sprague-Dawley albino rats. They confirm other experimental and clinical studies demonstrating an absence of adverse effects of photobiomodulation. Further, they provide essential safety data for the continued development and clinical application of PBM for the treatment of retinal degenerative disease.

Keywords: 615 neuroprotection • 600 mitochondria • 494 degenerations/dystrophies