An eye on long-duration spaceflight: Controversies, countermeasures and challenges

Area of Science:

• Space medicine
• Ophthalmology
• Neuroscience

Background:

• Space flight-associated neuroocular syndrome (SANS) affects two-thirds of astronauts on long-duration missions.
• SANS manifests as refractive changes, optic disc edema, and choroidal folds, with some changes persisting post-flight.
• The role of intracranial pressure in SANS development is debated, with recent focus on genetics and nutraceuticals.

Purpose of the Study:

• To review and discuss the controversies surrounding the pathophysiology of SANS.
• To explore potential countermeasures for SANS, considering intracranial pressure and genetic factors.
• To evaluate the translational application of therapies for idiopathic intracranial hypertension as SANS countermeasures.

Main Methods:

• Narrative review of existing literature on SANS.
• Analysis of the role of intracranial pressure and the 1-carbon metabolic pathway.
• Discussion of head-down tilt bed rest models for SANS research.
• Exploration of glucagon-like peptide 1 receptor agonists as potential countermeasures.

Main Results:

• Optic disc edema resolves post-flight, but choroidal folds and axial length changes persist.
• Head-down tilt bed rest is a key platform for studying SANS and testing therapies.
• Glucagon-like peptide 1 receptor agonists show potential for managing elevated intracranial pressure, relevant to SANS.

Conclusions:

• Further research is needed to clarify SANS pathophysiology, integrating intracranial pressure, genetic, and environmental factors.
• Targeted therapies, potentially adapted from idiopathic intracranial hypertension treatments, may offer effective countermeasures for SANS.
• Understanding individual genetic predispositions is crucial for developing personalized SANS prevention and treatment strategies.