Anterior segment biomechanics and intraocular pressure in microgravity: implications for future spaceflight studies

Spaceflight acutely but transiently elevates intraocular pressure (IOP), often attributed to cephalad fluid shift and choroidal expansion. We propose that anterior segment mechanics, including lens–iris diaphragm position and conventional outflow loading, may contribute to early IOP changes. Comparing phakic and pseudophakic eyes, paired with anterior segment OCT and complementary imaging aboard the International Space Station, could define mechanisms and inform astronaut screening and ocular risk mitigation.