Effect of rapid decompression on rat multifocal electroretinogram

Abstract

To observe the effect of rapid decompression on rat multifocal electroretinogram (mfERG) and to explore the characteristics of the retinal function impairment due to decompression sickness at early stage. Twenty rats were randomly divided into 4 groups: normal control (NC) group, safe decompression (SD) group, 0 h and 6 h after rapid decompression (RD0 and RD6) groups. The treated rats in safe decompression group and each rapid decompression group were exposed in hyperbaric cabin and air pressure in the cabin rose up to 1.0 MPa in 30 s and lasted for 5.5 min. The pressure decreased to normal pressure in 55 s as for the treatment of rapid compression while air pressure of safe decompression decreased to normal pressure according to an animal safe decompression protocol. The mfERG parameters of one eye each rat were recorded by RETIscan 3.15 system. Rapid decompression increased noise, delayed latent period and reduced amplitude in mfERG. The topographic map showed that the P1 wave response density in RD0 group was lower than that in NC and SD groups and higher than that in RD6 group in peripheral regions. The amplitudes of sum response density in NC, SD, RD0 and RD6 groups were (71.1 ± 7.5), (53.6 ± 9.3), (38.2 ± 13.1) and (18.4 ± 7.7) µV, respectively, and there was statistical difference among them (F = 17.313, P < 0.01). The P1 wave response densities of RD0 and RD6 groups were lower than that of NC group in 4 quadrants (P < 0.05) and the P1 wave amplitudes of RD0 and RD6 groups decreased in supranasal and supratemporal quadrants (P < 0.05). The P1 wave amplitudes of RD0 and RD6 groups were less than these of NC and SD groups in supranasal and supratemporal quadrants (P < 0.05). In 5 rings, the response densities of RD0 and RD6 groups were lower than these of NC and SD groups (P < 0.05) and the P1 and N1 wave amplitudes were less than these of NC and SD groups (P < 0.05). The P1 and N1 wave amplitudes of RD6 group were lower than those of RD0 group (P < 0.05). Rapid decompression can cause characteristic changes of mfERG and the major involved parts are superior retina and juxtaprepapillary region.