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  • Preventing Ocular Changes During Spaceflight

    By Jean Shaw
    Selected and reviewed by Neil M. Bressler, MD, and Deputy Editors
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    Journal Highlights

    JAMA Ophthalmology, August 2022

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    Can the changes to the optic nerve head and retina that occur during spaceflight be mitigated by brief in-flight appli­cation of 25-mm lower-body negative pressure? Pardon et al. addressed this question during a prospective cohort study. They found that long-duration spaceflight was associated with peri­papillary tissue thickening, decreased cup volume, and mild central macular thinning—and that exposure to lower-body negative pressure did not alter optic nerve head or retinal morphology.

    For this study, the researchers evalu­ated OCT scans of the optic nerve head and macula of 14 U.S. and internation­al crew members who completed six- to 12-month missions on the Internation­al Space Station. The OCTs were taken before, during, and after the missions. In-flight scans were obtained under normal weightless conditions as well as during exposure to lower-body negative pressure in 10- to 20-minute sessions. Pre- and postflight data were collected while crew members were in three pos­tures (seated, supine, and head-down tilt). Main outcome measures were changes in minimum rim width, optic cup volume, Bruch membrane opening height, peripapillary total retinal thick­ness, and macular thickness.

    Mean flight duration was 214 days. Ocular changes on flight day 150, as compared with preflight seated posture, included an increase in minimum rim width (33.8 μm; 95% confidence interval [CI], 27.9-39.7 μm; p < .001), decrease in cup volume (.038 mm3; 95% CI, .03-.046 mm3; p < .001), poste­rior displacement of Bruch membrane opening (–9 μm; 95% CI, –15.7 to –2.2 μm; p = .009), and decrease in macular thickness (fovea to 500 μm, 5.1 μm; 95% CI, 3.5-6.8 μm; p < .001). The ex­posure to lower-body negative pressure did not affect these parameters.

    These findings suggest that a longer duration of exposure to lower-body negative pressure may be needed to counter­act the fluid shift and resulting ocular changes that occur during missions to space, the authors said. They noted that other mechanisms may be involved in spaceflight-induced changes.

    The original article can be found here.