Abstract
Purpose :
To analyze flash visual evoked potentials (fVEP), pupil light reflex (PLR) and spectral-domain optical coherence tomography (SD-OCT) in healthy rat eyes.
Methods :
Adult male Long-Evans rats (300-350g) were studied. fVEP was recorded with subdermal wire electrodes. The amplitudes and latencies of waveforms were analyzed (N=6). The pupil diameters, the percentage of pupil constriction (CH) and the latencies of the constriction (CLAT) were evaluated in direct and consensual PLR (N=5). Structural properties of the retinal layers were assessed using SD-OCT (N=9). All results were provided as means ±SEM. Nonparametric signed rank test, one-way repeated measures analysis of variance and ANOVA on ranks were used for statistical analysis.
Results :
fVEPs at 0-N1 revealed amplitudes of -11.1±1.5 µV at latencies of 56.4±2.9 ms; P1-N1:
-16.5±1.6 µV at 21.1±2 ms; N1-P2: 27.9±2.5 µV at 47.3±3.2 ms. The baseline pupil diameter (Max/mm) was 2.3±0.04. The pupil diameters and latencies at the peak of constriction (Min/mm, CLAT/sec) after light stimulation were: 1.3±0.08, 0.34±0.01 in white (4.3 log LUX); 1.5±0.08, 0.35±0 in red (622 nm, 3.3 log LUX); 1.4±0.09, 0.34±0.02 in green (528 nm, 4.5 log LUX); and 1.2±0.05, 0.29±0 in blue (463 nm, 3.9 log LUX) light illumination. There were significant differences of CLAT in blue light vs. red light (p<0.001), green light (p=0.017) and white light (p=0.015). There were significant differences of Max vs. Min in all light stimulations in both the direct and consensual PLR (p<0.05). There was significant difference of CH between the direct and consensual PLR only with the blue light stimulation (52±3% vs. 48±3%, p=0.03). Total retinal thickness (µm) in central regions were measured as 198.7±5.9 (disk), 193±4.2 (nasal), 200.1 ±2.3 (temporal), 180.8±2.6 (inferior, vs. disk p=0.02) and 195.3±1.9 (superior). The thickness of retinal nerve fiber layers (NFL/µm) were 41.0±2.6 (disk), 23.6±2.2 (nasal), 26.6±2.0 (temporal), 17.9±1.3 (inferior) and 17.8±1.0 (superior). There were significant differences between NFL at the disk and all other regions (p<0.001), the temporal vs. superior (p=0.009) and inferior (p=0.008).
Conclusions :
Baseline characterization of fVEP, PLR and SD-OCT provided useful information about visual function and retinal structure, with which we plan to study on traumatic visual dysfunction in rats.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.