Abstract
Purpose: :
To determine if the results from different tests of visual function can be directly compared in a rodent models of retinal degeneration with and without various rescue strategies.
Methods: :
In the course of assessing various cell–based therapies using the RCS rat model we have routinely employed three ways of testing visual function dark–adapted ERG, spatial acuity to moving stripes and luminance threshold responses recorded from the superior colliculus. Longer–term experiments assessing promising treatments were also performed with survival times out to P210 where again optomotor performance was tested followed by tectal recordings. A retrospective comparison of 30 animals from various experimental groups differing in treatments and time points was made to determine if any correlation existed between the various tests. All animals used were pigmented dystrophic RCS rats.
Results: :
ERG results at P60 & P90 showed no correlation with either optomotor or tectal measurements. The optomotor and tectal thresholds did show a correlation and could be plotted against each other using MS Excel. Very similar results were obtained for average and peak tectal thresholds plotted against optomotor relative acuity reporting trend line y=–0.1049x + 0.6661, R2= 0.695 for average luminance threshold and y=–0.1087x + 0.5863, R2= 0.73 for peak luminance threshold. The only criteria for animals in this assessment were that they were dystrophic RCS with or without transplants and that data was available from comparable time points: this ensured that a wide sample of visual performances was recorded.
Conclusions: :
A common question in this research is how do the different functional tests compare. Optomotor and luminance thresholds correlate, but ERG data did not. This is useful as it confirms that the optomotor system can be used as a quick method of screening visual function in models of retinal degeneration to assess treatment efficacy.
Keywords: retinal degenerations: cell biology • electrophysiology: non-clinical • visual acuity