Abstract
Purpose: :
Previous studies in dogs and cats have shown efficacy of the handheld multispecies ERG (HMsERG) unit in the early diagnosis of hereditary retinal disease processes. We wanted to evaluate if the HMsERG was a reliable tool to use also in conjunction with phenotypic characterization of hereditary retinal diseases in mouse models.
Methods: :
Conventional table-top full-field Xenon flash ERG equipment (Toennies Multiliner Vision, Viasys Healthcare, Hoechberg, Germany) was used in comparison to the HMsERG (RetVet Corp, Columbia, MO), which includes a mini-Ganzfeld stimulator utilizing white LED's for both stimulation and background light. Scotopic and photopic intensity series (scotopic: 0.1mcd.s/m2 to 25 cd.s/m2, and photopic: 10mcd.s/m2 to 25 cd.s/m2) and flicker series were obtained in anesthetized wildtype and functionally rod- (Cnga3-/-) or cone-specific (Rho-/-) mice.
Results: :
The ERG waveforms and their changes with intensity and frequency were remarkably similar when results of intensity and flicker series using the two ERG units were compared. The absolute scotopic and photopic ERG amplitudes for the HMsERG were found to be lower than those obtained with the Toennies equipment, relatively more so for rod than for cone responses, presumably due to the LED light emission spectrum that undergoes a dip at the peak sensitivity for (murine) rods.
Conclusions: :
The HMsERG unit can be used to reliably obtain low and high intensity responses and flicker series, with waveforms comparable to those obtained with a conventional table-top Ganzfeld system. Conformity may be further improved by refinement of the LED emission spectrum. The portable HMsERG appears to be a useful tool in phenotypic characterization of retinal diseases in rodents in various laboratory settings.
Keywords: electroretinography: non-clinical • retinal degenerations: hereditary • photoreceptors