In-vivo observing effects of the microgravity environment on zebrafish eyes using optical coherence tomography

Abstract

Microgravity, vacuum, and high-intensity ultraviolet waves are widely known characteristics of space. These different environments from the earth affect physical changes including ocular tissue changes while astronauts stay in the universe. The changes in ocular tissue in the space environment, also known as visual impairment intracranial pressure (VIIP) syndrome, including fundus optic disc edema, hyperopic drift, choroidal folds, cotton spots, and permanent fundus damage could influence astronauts' vision system and ability of space operations. Especially, hyperopic drift by posterior flattening and folded retina by choroidal folds are reported to affect the retina's structures as a vision sensor directly. To investigate microgravity's effect on ocular tissues and vision, previous research on earth are used special facilities and various microgravity simulators, including head-down tilt bed-rest and random positioning machines. This study suggests that an experiment expose wild-type zebrafish to microgravity using a rotary cell culture system (RCCs) applied to experiments using cell and zebrafish's embryos in microgravity. Unlike previous research using zebrafish's embryos and larva, adult and growing zebrafish were employed in this study for observing ocular changes in simulated space environments. After exposing zebrafish to microgravity, in-vivo zebrafish's eye images were acquired by custom-built optical coherence tomography (OCT). This research for presenting the new method for small animal experiments in microgravity environments could be applied to investigate the influence of staying in the universe on an animal model with ophthalmic diseases.