Advanced ocular drug delivery in microgravity: Nanotherapeutic applications as cardiovascular and ophthalmic countermeasures.

Extended space missions significantly affect astronaut health, leading to various systemic and ocular conditions. The ocular surface and cardiovascular system are particularly susceptible to the unique environment within the spacecraft. This can often lead to pathologic issues such as radiation-induced accelerated atherosclerosis (RIAA), spaceflight-associated neuro-ocular syndrome (SANS) and spaceflight-associated dry eye syndrome (SADES). While traditional treatments for SADES, such as artificial tears and lubricants, provide short-term relief, they may lose effectiveness during long-duration spaceflight. In this context, nanomedicine offers promising solutions for the controlled and targeted delivery of therapeutics, including drugs and biologics. This review assesses the spectrum of ocular health and cardiovascular changes in astronauts, highlights the limitations of existing therapeutic measures, and explores how nanotechnology-based approaches can overcome these limitations by significantly enhancing drug delivery in microgravity. We further discuss the need for rigorous validation to improve the management of ocular and cardiovascular in future space exploration.