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Identifying Predisposing Factors for Hyperopic Shift in Long-Duration Spaceflight
Aerospace Medicine and Human Performance
|August 1, 2026
Summary
Astronaut age is the primary risk factor for hyperopic shift, a vision change during long space missions. Mission duration and body weight also showed weaker links to this spaceflight-associated neuro-ocular syndrome (SANS) component.
Area of Science:
- Space medicine
- Ophthalmology
- Human physiology in space
Background:
- Spaceflight-associated neuro-ocular syndrome (SANS) is a significant health concern for astronauts on missions longer than 30 days.
- Hyperopic shift, a component of SANS, involves a change in the eye's refractive power.
- Understanding risk factors for SANS is crucial for developing countermeasures and ensuring astronaut health.
Purpose of the Study:
- To retrospectively analyze age, mission duration, and preflight body weight as potential risk factors for hyperopic shift in astronauts.
- To identify key predictors of hyperopic shift to inform prevention strategies for long-duration spaceflight.
- To provide insights into conditions similar to SANS that may occur on Earth.
Main Methods:
- Retrospective analysis of deidentified data from NASA's Medical Evaluation Documents, Volume B database.
- Inclusion of astronauts who participated in space missions exceeding 30 days.
- Assessment of refractive outcomes using manifest refraction (MR) and manifest refraction spherical equivalent (MRSE), with Spearman's rank correlation to analyze risk factor associations.
Main Results:
- Age demonstrated a significant positive correlation with hyperopic shift (MR: r = 0.373; MRSE: r = 0.353).
- Mission duration showed a positive correlation with MR (r = 0.253) and a nonsignificant trend with MRSE (r = 0.195).
- Preflight bodyweight significantly correlated with MRSE (r = 0.242) and showed a nonsignificant trend with MR (r = 0.207).
Conclusions:
- Age is identified as the strongest predictor of hyperopic shift in long-duration spaceflight.
- Mission duration and preflight body weight exhibit weaker positive associations with hyperopic shift.
- Further research is recommended to define SANS criteria and investigate the relationship between risk factors and other SANS manifestations.
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