Differential Functional Changes in Visual Performance during Acute Exposure to Microgravity Analogue and Their...

Area of Science:

• Spaceflight physiology
• Neuro-ophthalmology
• Human factors in aerospace medicine

Background:

• Spaceflight-Associated Neuro-Ocular Syndrome (SANS) poses a risk to astronauts.
• Current diagnostic methods for SANS are limited.
• The underlying causes of SANS require further investigation.

Purpose of the Study:

• To explore differential visual system performance (central vs. perimacular) as a potential SANS biomarker.
• To assess changes in visual function under simulated microgravity conditions.
• To evaluate the utility of reaction time tests for SANS detection.

Main Methods:

• Utilized a simple reaction time (SRT) task with central and perimacular visual stimuli.
• Simulated microgravity using head-down tilt (HDT) bed rest (-6° and -15°).
• Analyzed SRT distribution parameters in response to varying gravitational loads.

Main Results:

• Acute simulated microgravity (HDT) caused significant changes in perimacular vs. central retinal SRT distributions.
• Increased mean, standard deviation, and tau component of the ex-Gaussian function were observed in the perimacular area.
• These findings indicate detectable alterations in visual processing under simulated microgravity.

Conclusions:

• Functional testing of the perimacular retina shows promise for early SANS detection.
• Complementary assessment of perimacular function alongside central vision testing is recommended.
• Future SANS diagnostics should incorporate evaluation of extra-macular regions, especially near the optic disc.