Hypercania’s Effect on Ocular Glymphatic Function

Abstract

The consequences of a hypercapnic environment underscore negative alterations in crucial physiological processes in the CNS. This project studied how elevated CO₂ impacts the ocular glymphatic system by having participants breathe elevated CO₂ and undergo delayed MRI following gadolinium contrast administration. Specifically looking at whether changes in physiological responses (blood pressure, respiration, heart rate, etc.) were correlated with change in ocular signal intensity between the ambient air and CO₂ data collection sessions. Associations of R = 0.44 and 0.38 for diastolic blood pressure and respiration rate were found, respectively, with changes in signal intensity in the vitreous chamber of the eye. These values were not statistically significant, given the small sample size (n=12); with more participants these associations might achieve the significance threshold. This would suggest that the physiological responses that typically occur with elevated CO₂ levels may be a driver to changes in the ocular glymphatic system, potentially contributing to SANS. The findings support the need for further studies on astronaut ocular health.