Spaceflight associated neuro-ocular syndrome (SANS): a systematic review, implications for the sans case definition

ABSTRACT

Background

Astronauts undergoing long-duration space flights (LDSF) often experience a unique set of neuro-ocular findings known as Spaceflight Associated Neuro-ocular Syndrome (SANS). However, the exact mechanisms and the true incidence of SANS remain unclear. This paper aims to review the existing literature on SANS, focusing on its incidence and sequence of findings, and to provide a comprehensive understanding of this condition.

Research design and methods

Studies reporting SANS and optic disc edema in astronauts from PubMed, Scopus, and WOS have been collected. Eligible studies were selected based on stringent inclusion criteria. Statistical analysis utilized R software with random effect models for them, and heterogeneity was assessed using I2 and chi-squared tests.

Results

Our study includes 19 studies that met the inclusion criteria, which encompassed 294 participants. Included studies revealed that optic disc edema and choroidal folds were highly prevalent, with proportions of 75% and 71%, respectively. Hyperopic shifts (95%CI 0.51, 0.76, I2 = 0%) were also statistically significant, appearing gradually and persisting even after astronauts returned to Earth.

Conclusion

This study provides a comprehensive assessment of SANS in astronauts. The study suggests that the current clinical definition of SANS may underestimate its true incidence and proposes the inclusion of quantitative metrics to enhance sensitivity and accuracy in diagnosis.

KEYWORDS:

• SANS
• neuro-ocular findings
• spaceflight
• astronaut health
• meta-analysis

Acknowledgments

The authors wish to acknowledge, recognize, and thank anonymised MD and anonymized OD, PhD for reviewing this manuscript and providing helpful comments for revision.

Conflict of interest statement

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Data availability statement

The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/17469899.2023.2296884

Additional information

Funding

This paper was not funded.