A recent Investigative Ophthalmology & Visual Science study has shed new light on how extended exposure to microgravity can alter the human eye’s choroidal structure – findings that deepen our understanding of Spaceflight Associated Neuro-ocular Syndrome (SANS). The research, led by the Centre de Recherche de l'Hôpital Maisonneuve-Rosemont in Montréal, Québec, applied advanced deep learning algorithms to optical coherence tomography (OCT) data from astronauts to assess spatial and pulsatile changes in the choroid before, during, and after space missions.
Twelve astronauts were analyzed using OCT macular videos and volumes and retrained SegFormer deep learning models for precise choroidal segmentation and vascularity assessment. The results revealed significant increases in both choroid thickness and luminal area post-flight, with inflight imaging further confirming substantial volume and vascularity expansion. Importantly, pulsatile changes in luminal area also increased significantly, although choroidal thickness pulsatility remained unchanged.
These changes support the hypothesis that microgravity leads to venous congestion and blood volume redistribution, causing choroidal swelling and possibly contributing to SANS-related symptoms, such as optic disc edema and visual disturbances. The findings also align with previous studies showing sustained choroidal thickening up to 90 days post-return and highlight the potential biomechanical impact of these volume fluctuations on
Understanding how the choroid responds to weightlessness is vital for safeguarding visual function on long-duration space missions, and may have broader implications for terrestrial diseases involving vascular and pressure dysregulation, the authors conclude.
