Abstract
Purpose :
Light-Induced Retinal Degeneration (LIRD) is a powerful method to assess the response of photoreceptors to damage. Traditionally performed using fluorescent lamps on albino animals, this tool is unsuitable for pigmented animals. We wanted to model LIRD in commonly used C57Black mice that carry a hypomorphic RPE65 allele. We came across a previously developed method using LED lamps and mouse cages to create small, inexpensive light damage boxes and have successfully implemented this method to achieve LIRD in C57Black animals.
Methods :
We obtained LED lights to reproduce the >60k lux light intensity reported by a previous study. We adapted them with a 3-D printed fitted lid to securely attach the lights to the mouse cages. The light intensity was adjustable from 5,000 to 63,000 lux with the adjustment of a dimmer switch. Low-noise fans had to be equipped to the boxes. These allowed the boxes to maintain an acceptable temperature range of (25-27°C) while lights were in operation with little disturbance to the mouse. Mice used were C57Black, and 129/Sv reared in cyclic lighting conditions. The eyes were dilated with Tropicamide 1% and Phenylephrine Hydrochloride 2.5% (in a ratio 1:1) 10 minutes before light damage. The light damage was performed between 7-11 pm, at varying light intensities ranging from 20-60k lux after 24hr dark adaptation. The mice were returned to dark for 24hrs following light damage and then were returned to the animal facility and maintained with cyclic light conditions. Electroretinography (ERG) was performed at 24hrs and one week post light damage to evaluate visual function.
Results :
We were able to build light boxes for about $200-300 per box, depending on the prices of LED studio lights, fans, and plastic filament. The lightbox was powerful enough to induce a significant reduction in visual function in C57Black mice following four hours and 129/Sv after only 1 hour of exposure at >60000 lux. The results also indicate that visual function is significantly reduced by 24 hrs and remains reduced at seven days.
Conclusions :
This method allows for a rapid assessment of mice models such as the C57Black or 129/Sv background. In addition, most labs can quickly build the light damage box, which can alleviate some of the barriers to studying retinal disease mice models under light stress conditions.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.