Abstract
Purpose: :
We have succeeded in generating a rhodopsin Pro347Leu transgenic (Tg) rabbit, a model of retinal degeneration (Kondo M et al. IOVS, 2009). We have studied the retinal function of these Tg rabbits using full-field electroretinograms (ERGs) and found that the oscilatory potentials (OPs) were better preserved than the a- and the b-waves (Sakai et al, IOVS, 2009). The purpose of this study was to investigate the retinal function in localized areas in Tg rabbits using the focal cone ERG techniques.
Methods: :
Six pigmented Tg and six wild type (WT) rabbits were studied. Focal cone ERGs were recorded using a modified infrared fundus camera which allowed monitoring of the stimulus spot on the fundus during the recordings. A 15 degrees stimulus spot was used to elicit the focal cone ERGs from five different retinal areas (central, upper, lower, nasal, and temporal retinal areas). The amplitudes and implicit times of the b-waves and oscillatory potentials (OPs) were analyzed.
Results: :
The b-wave amplitudes of the focal cone ERGs in Tg rabbits were smaller than those of WT rabbits at all five locations. The decrease in the amplitude in the Tg rabbits was greatest at the central retinal area (Tg=0.6±0.3 µV at 3 months; 0.3±0.3 µV at 5 months; WT=3.1±0.8 µV). The amplitudes of the OPs tended to be better preserved at the upper retinal area (1.0± 0.6 µV) than the other retinal areas in Tg rabbits, and were not significantly different from those of WT rabbits (1.0±0.6 µV).
Conclusions: :
These results indicate that the retinal dysfunction of Tg rabbits were most severe in the central retinal area corresponding to the findings of retinal histology (Kondo et al. IOVS, 2009). Our results suggest that there are regional variations in the preservation of OPs in Tg rabbits.
Keywords: electroretinography: non-clinical • retinal degenerations: hereditary • degenerations/dystrophies