Late developments of optic disc edema or choroidal folds were documented in 2 crew members who traveled to the International Space Station for a spaceflight mission that lasted 1 year, according to a report published in JAMA Ophthalmology.
Researchers reviewed 2 cases fromInternational Space Station missions exceeding a 6-month duration and their associations with worsening spaceflight-associated neuro-ocular syndrome. The main outcome measures, obtained via optical coherence tomography (OCT), were minimum rim width and peripapillary total retinal thickness, and participants were tested before, during, and after spaceflight. Other ocular changes noted were peripapillary retinal edema, axial length, anterior chamber depth, and refraction. In its analysis, the study compared ocular changes in 2 crew members with cohort crew members from a 6-month mission (n=11).
In both participants 1 and 2, the study found an increase in minimum rim width (561 µm and 539 µm, respectively, at flight day 270) and total retinal thickness (547 µm at flight day 90 and 528 µm at flight day 210) in both 1-year spaceflight participants throughout the duration of spaceflight exposure to the maximal observed change from preflight. These results reflect an increase of 149 µm and 56 µm, respectively, for minimum rim width and 135 µm and 45 µm for total retinal thickness. The researchers note that the other ocular changes analyzed were similar between the 1-year participants and the 6-month cohort.
The researchers explain that, while the results of this study support their hypothesis, they may not be generalizable to other 1-year spaceflight mission participants. Because this study only quantifies choroidal folds, it did not collect data on other types of folds that have been documented in past spaceflight research. Additionally, the study emphasized a future need to identify the factors contributing to these ocular changes.
“As future spaceflight missions are planned to increase in duration and extend beyond low Earth orbit, further observation of astronaut ocular health on spaceflight missions longer than 6 months in duration may be warranted,” they conclude.
Macias BR, Ferguson CR, Patel N, et al. Changes in the optic nerve head and choroid over 1 year of spaceflight. JAMA Ophthalmol. Published online April 29, 2021. doi:10.1001/jamaophthalmol.2021.0931