Analysis of the anatomical and functional ocular changes related to spaceflights

Abstract

Purpose : To examine early changes in ocular physiology following exposure to microgravity and asses these changes as a risk factor for Spaceflight Associated Neuro-Ocular Syndrome (SANS).

Methods : AX-1 mission to space was sent to the international space station by AXIOM and NASA in April 2021 for 17 days. A 64-year-old male astronaut participated in our study. We conducted before and after-flight full ophthalmic examination and multimodal imaging extended sessions that included anterior and posterior segment imaging. All images were reviewed separately by retina, glaucoma, and cornea specialists for structural alterations. Additionally, optical coherence tomography angiography (OCTA) imaging is not a standard NASA protocol and was conducted for the first time in history. 512 OCTA scans, grouped into 5 regional groups for t-test calculations, were processed by image processing experts. The aim of image processing was to identify and count the points (pixels) containing flow signal in each image while separating the flow signal in the retina from the choroid.

Results : In our study, OCT angiography studies demonstrated a significant decrease in the macular choroidal and retinal flow signal of 29%, 8.5% respectively in the right eye and 11%, 6.5% respectively in the left eye after the spaceflight as compared to baseline (p<0.0001 both eyes). Focal alterations in choroidal thickness and Haller vessels diameter were noted but did not reach statistical significance. No alternations were found in other structures or functions. The astronaut reported a need for reading glasses while in space.

Conclusions : Significant alternations in sub-macular choroidal blood flow were noted in this study after a short period of time in space. These should be further studied as possible risk factors for SANS.
We recommend that future space flights include OCTA imaging as a standard protocol

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.