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Spaceflight-Associated Epiphora Mechanisms and Countermeasures.

Blake Douglas Katsev, Ryung Lee, Joshua Ong

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    |March 27, 2026
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    Summary
    This summary is machine-generated.

    Excessive tearing (epiphora) in astronauts is linked to dry eyes and impaired tear drainage due to microgravity. Countermeasures focus on tear film maintenance and radiation protection.

    Keywords:
    epiphoralacrimal systemmicrogravityreflex tearingspaceflight

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    Area of Science:

    • Ophthalmology
    • Aerospace Medicine
    • Space Physiology

    Background:

    • Epiphora, or excessive tearing, is common in dry eye patients and astronauts.
    • Astronauts experience higher rates of epiphora due to spaceflight conditions.

    Purpose of the Study:

    • To review the pathophysiology and mechanisms of epiphora in spaceflight.
    • To identify risk factors associated with spaceflight-induced epiphora.
    • To discuss potential countermeasures for spaceflight-associated epiphora.

    Main Methods:

    • Literature review of medical databases (Embase, PubMed, etc.) and reliable secondary sources (NASA webpages).
    • Search strategy identified 94 articles, with 67 deemed relevant for the study.

    Main Results:

    • Spaceflight-associated epiphora has a multifactorial cause, involving reflex tearing and lacrimal drainage obstruction.
    • Dry eyes trigger reflex tearing, while microgravity and fluid shifts impede tear drainage.
    • Radiation exposure can cause corneal irritation and gland atrophy, affecting tear film stability.

    Conclusions:

    • Spaceflight-associated epiphora results from reflex tearing and impaired tear drainage.
    • Countermeasures include tear film maintenance, managing fluid shifts, and radiation protection.