Objective:

To establish a framework for diagnosing and managing spaceflight-associated neuro-ocular syndrome (SANS) affecting astronauts during long-duration spaceflights.

Approach:

• Expert Consensus: A consensus was developed by NASA SANS specialists and experts in cerebrospinal fluid disorders to harmonize case identification and guide clinical decision-making.

Key Findings:

• 81% of NASA astronauts assessed after long-duration spaceflight exhibited at least one feature of SANS.
• Early changes in SANS are common in microgravity, with severity increasing with mission duration and repeated exposure.
• Structural changes such as globe flattening and axial length alteration can persist for years after returning to Earth.
• Optical coherence tomography (OCT) is central to the proposed diagnostic approach, with specific increases in retinal thickness indicating optic disc edema.

Interpretation:

SANS presents significant clinical risks for astronauts, including hyperopic shift and visual field changes, and requires standardized diagnosis and monitoring.

Limitations:

• Astronaut cohorts are small, and evidence regarding SANS is limited.
• The pathophysiology of SANS remains unresolved, with no terrestrial disease serving as a perfect model.

Conclusion:

SANS represents an emerging neuro-ophthalmic condition that necessitates careful monitoring and credible countermeasures as spaceflight duration increases.

Sources:

• Eye Journal