Changes of ocular fundus hemodynamics and retinal and choroidal thickness after tail suspension for 2 weeks in rats

Objective　To investigate the effects of simulated 2-week microgravity on the ocular fundus hemodynamics of central retinal artery and the retinal and choroidal thickness in autogenous rats. Methods　Eight healthy SD rats were designed in self-control, designed for the control before tail suspension, the tail suspension for 1, 4, 7 and 14 d. A rat model of simulated microgravity method was established by tail suspension. The peak maximum systolic velocity (PSV) of central retinal artery (CRA) in rats was detected and analyzed by color Doppler ultrasonography. The retinal and choroidal thicknesses were measured by the enhanced depth imaging spectral-domain optical coherence tomography (EDI SD-OCT). Results　The PSV value in each different period after tail suspension was decreased compared with that in the control before tail suspension (P 0.05), but there was a significant difference between the tail suspension for 1 d and the tail suspension for 14 d (P 0.05). The choroidal thickness was lower in the control before tail suspension than that in each different period after tail suspension (P<0.05). Compared with the tail suspension for 1 d, the choroidal thickness of the rats was significantly increased in the tail suspension for 4, 7 and 14 d respectively (P<0.05). Conclusions　Two-week simulated microgravity environment has significant effects on the fundus blood flow and choroid thickness in rats, but has no obvious effect on the retinal thickness in rats. The fundus flow velocity would decrease and choroid thickness would increase with the prolongation of the tail suspension time. DOI: 10.11855/j.issn.0577-7402.2021.01.02