The Case for Expanding Visual Assessments During Spaceflight

Spaceflight associated neuro-ocular syndrome (SANS) is one of the potential barriers to human long-duration spaceflight (LDSF), including a manned mission to Mars. While a large barrier, the pathophysiology of SANS is not well understood, and functional and structural findings from SANS continue to be further characterized. Currently on the International Space Station (ISS), scheduled visual assessments are static visual acuity, Amsler grid, and a self-reported survey. Additional visual assessments may help the understanding of this neuro-ophthalmic phenomenon, as well as the effects of spaceflight of overall ocular health. In this paper, a case is made for expanding scheduled visual assessments to include dynamic visual, contrast sensitivity (CS), visual field testing, and virtual reality-based metamorphopsia assessment during spaceflight. These further assessments may play a key role in helping to determine the structural and functional changes associated with SANS, which are crucial to maintain astronaut vision during LDSF, as well as for developing countermeasures. Finally, a brief discussion is provided about current challenges to expanding visual testing during spaceflight and potential solutions to these barriers, specifically head-mounted visual assessment technology.