Characterization of the pupil light reflex, electroretinogram and tonometric parameters in healthy rat eyes

Abstract

Purpose. To characterize the pupil light reflex (PLR), electroretinographic (ERG) and tonometric parameters in healthy rat eyes. Methods. Brown Norway rats were used for experiments. The PLR was evaluated with a computerized pupillometer (n = 27), ERGs were recorded simultaneously from both eyes (n = 27) and IOP was measured with a Tonopen (n = 15). Results. The analysis of the PLR parameters confirmed that the consensual PLR had a significantly smaller amplitude (0.1-0.2mm; p = 0.03) and an increased latency time (p = 0.001) compared to the direct PLR. Electroretinography revealed an a-wave amplitude of 207.2 ± 13 µV with a latency of 25.6 ± 0.7 ms, and a b-wave 554.3 ± 24.5 µV with a latency of 21.4 + 1.8 ms. The flicker ERG recording revealed amplitudes of 40.6 ± 2.4 µV. Tonometry measurements revealed that isoflurane, but not halothane, anesthesia suppressed the IOP (non-anesthetized: 25.3 ± 1.0 mmHg; 1 % halothane + 30% NO: 26.2 ± 1.1 (p > 0.1); 1 % isoflurane + 30 % NO: 20.1 + 1.6 (p < 0.05)). Conclusions. Consensual PLR in rats has a relative deficit compared to the direct PLR. Isoflurane anesthesia has a suppressive effect on the IOP in healthy rat eyes.