Abstract
Purpose::
C-waves constitute one of the series of slow potentials of electroretinograms (ERGs) that are thought to arise from the retinal pigment epithelium (RPE). Recording c-waves with ease will be useful in evaluating RPE function for regenerative treatment of the retina. Here we describe a noninvasive means of recording c-waves from mice using contact lens electrodes with built-in white light-emitting diodes (LEDs). These electrodes can also be used for full-field conventional ERGs.
Methods::
We recorded ERGs from 8 - 10 week-old RPE degeneration model and naïve C57BL/6 mice after overnight dark adaptation. We experimentally induced RPE degeneration in 10-week old male C57BL/6 mice with a single injection of either 50 or 70 mg/kg of 1% sodium iodate through the tail vein. We then simultaneously recorded ERGs from both eyes because integrated LEDs do not stimulate the other eye.
Results::
We recorded a positive wave with a peak latency of approximately 2 seconds after the b-wave in naïve C57BL/6 mice. This wave extremely reduced after light adaptation. At one day after injecting mice with 50 mg/kg of sodium iodate, we recorded a negative wave with a latency of approximately 1 second after an enhanced b-wave. Thereafter, the negative wave shifted towards higher stimulation intensity and the b-wave amplitude was obviously reduced. Changes in the b- and c-waves were more intense in mice injected with 70, than with 50 mg/kg of sodium iodate. We did not find any positive waves such as those from naïve mice after sodium iodate injection.
Conclusions::
A positive wave that followed the b-wave in naïve mice was recorded using contact lens electrodes with integrated white LEDs. This positive wave diminished after light adaptation. Because the positive wave was not recorded in the RPE degeneration model, it can be considered as a c-wave. This procedure could be a practical means of evaluating RPE function in mice.
Keywords: electroretinography: non-clinical • retinal pigment epithelium • degenerations/dystrophies