Spaceflight-Associated Epiphora Mechanisms and Countermeasures

Spaceflight-associated epiphora has a multifactorial etiology related to both reflex tearing and obstruction of the lacrimal drainage system. Dry eyes are closely associated with epiphora in space as the result of ocular irritation causing reflex tearing. Decreased tear drainage may result from the lack of gravitational assistance and the cephalad fluid shift which may create a functional obstruction of the lacrimal drainage system. While primarily a concern with chronic exposure, radiation may irritate the cornea, cause lacrimal and Meibomian gland atrophy, and disrupt tear film stability. Potential countermeasures include maintaining the tear film, mitigating the cephalad fluid shift, and protecting from radiation. Katsev BD, Lee R, Ong J, Gibson CR, Mader TH, Waisberg E, Lipsky W, Sampige R, Berdahl J. Spaceflight-associated epiphora mechanisms and countermeasures. Aerosp Med Hum Perform. 2026; 97(4):272-278.