Abstract
Purpose :
To characterize the changes of flash visual evoked potential (fVEP) and flash electroretinography (fERG) induced by blast exposure in rats.
Methods :
Anesthetized adult male Long-Evans rats were positioned in a compressed air-driven shock tube with left side facing the incoming blast wave. In this orientation, the head underwent a significant acceleration in the horizontal plane. Rats received a single blast wave exposure with peak overpressure of 207±10kPa and a positive phase duration of 3.30±0.06ms. fVEP and fERG were recorded prior to, and at 72h and 1, 2, 4, and 8 weeks post exposure. fVEP was recorded for both eye (OU), right eye (OD) and left eye (OS) stimulations using subdermal wire electrodes. The amplitudes and latencies of waveforms of 0-N1, P1-N1 and N1-P2 were analyzed (n=5). fERG was recorded simultaneously from both eyes using contact lens electrodes. The amplitudes and latencies of a-wave and b-wave were evaluated (n=5). One way RM ANOVA, RM ANOVA on Ranks and nonparametric Signed Rank Test were used for statistical analysis.
Results :
For fVEP in OU stimulation, the wave amplitude of 0-N1 were significantly decreased at 8wks post exposure (vs. the baseline p=0.027). There were no significant differences in P1-N1 and N1-P2. In OD stimulation, the wave amplitudes of 0-N1, P1-N1 and N1-P2 were significantly decreased at 8wks post exposure (vs. the baselines p=0.012, 0.046 and 0.009). In OS stimulation, there were no significant changes of wave amplitudes being observed. For fVEP latencies in OD stimulation, there were only significant differences in P1-N1 at 72h, 1w and 2wks post exposure (vs. the baseline p=0.019, 0.026 and 0.006). There were no significant differences of the latencies in OS or OU stimulations. fERG b-wave amplitudes in OD were significantly decreased at 72h and 2wks post exposure (vs. the baseline p=0.024 and 0.013). There were no significant differences of b-wave amplitude in OS, and a-wave amplitudes in both OD and OS. There were no significant changes of fERG latencies in OD and OS in both a-wave and b-wave.
Conclusions :
The single blast exposure resulted in abnormal wave amplitudes and latencies in fVEP and fERG in rats. The head accelerations may cause blast related TBI and responsible for such changes. The morphological studies in visual neurons will be useful to elucidate the mechanisms of such visual dysfunction.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.