July 2019
Volume 60, Issue 9
Open Access
ARVO Annual Meeting Abstract  |   July 2019
Sustained Ocular Venous Fluid Shift During Spaceflight May Contribute to Optic Disc Edema
Author Affiliations & Notes
  • Karina Marshall-Goebel
    Cardiovascular & Vision Laboratory, NASA Johnson Space Center, KBRWyle, Houston, Texas, United States
  • Brandon Macias
    Cardiovascular & Vision Laboratory, NASA Johnson Space Center, KBRWyle, Houston, Texas, United States
  • Steven Laurie
    Cardiovascular & Vision Laboratory, NASA Johnson Space Center, KBRWyle, Houston, Texas, United States
  • Stuart Lee
    Cardiovascular & Vision Laboratory, NASA Johnson Space Center, KBRWyle, Houston, Texas, United States
  • David Martin
    Cardiovascular & Vision Laboratory, NASA Johnson Space Center, KBRWyle, Houston, Texas, United States
  • Scott Dulchavsky
    Henry Ford Hospital, Detroit, Michigan, United States
  • Alan Hargens
    University of California, San Diego, San Diego, California, United States
  • Michael B Stenger
    NASA Johnson Space Center, Houston, Texas, United States
  • Footnotes
    Commercial Relationships   Karina Marshall-Goebel, None; Brandon Macias, None; Steven Laurie, None; Stuart Lee, None; David Martin, None; Scott Dulchavsky, None; Alan Hargens, None; Michael Stenger, None
  • Footnotes
    Support  NASA Human Research Program
Investigative Ophthalmology & Visual Science July 2019, Vol.60, 2303. doi:
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      Karina Marshall-Goebel, Brandon Macias, Steven Laurie, Stuart Lee, David Martin, Scott Dulchavsky, Alan Hargens, Michael B Stenger; Sustained Ocular Venous Fluid Shift During Spaceflight May Contribute to Optic Disc Edema. Invest. Ophthalmol. Vis. Sci. 2019;60(9):2303.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : The Spaceflight Associated Neuro-ocular Syndrome (SANS) is characterized by the development of optic disc edema, chorioretinal folds, globe flattening, and/or hyperopic shifts in astronauts during 6-month missions on the International Space Station (ISS). We hypothesize that a weightlessness-induced chronic headward fluid shift within the venous system contributes to these ocular changes.

Methods : Astronauts (n=10) were studied before flight (seated and supine posture) and ~150 days into a 6-month mission on the ISS. Ocular and vascular measures included optical coherence tomography (OCT; Spectralis, Heidelberg Engineering) assessments of sub-macular choroid thickness and peripapillary total retinal thickness (TRT; segmented from Bruch’s membrane to the internal limiting membrane); ultrasound-derived internal jugular vein (IJV) cross-sectional area (GE VividQ) and non-invasive IJV pressure (Veinpress); and intraocular pressure (IOP; iCare pro pre-flight and TonoPen in-flight). Repeated-measures ANOVA with Tukey’s post-test was used to determine the mean change between conditions; data are presented as group mean ± standard deviation.

Results : The mean IJV area increased from 9 ± 6 mm2 in the seated position to 83 ± 27 mm2 in the supine position on Earth and to 64 ± 31 mm2 during spaceflight (P<.001). Similarly, mean IJV pressure increased from 4.3 ± 1.6 mmHg in the seated position to 16.6 ± 5.6 mmHg in the supine position on Earth and to 14.4 ± 5.3 mmHg in-flight (P<.001). No significant changes in sub-macular choroid thickness or TRT were detected during the acute preflight posture change, however after 150 days of weightlessness, choroid thickness increased by 50 ± 37 µm (P<.05) and TRT increased by 26 ± 32 µm (P=.05) relative to preflight seated values. IOP remained within a normal range in weightlessness, averaging 15.4 ± 2.1 mmHg after 150 days of spaceflight, compared to 14.8 ± 2.7 mmHg and 15 ± 1.1 mmHg pre-flight in the seated and supine positions, respectively.

Conclusions : Although a transient posture-induced venous fluid shift has no effect on choroidal or retinal thickness, a sustained, unrelenting cephalad fluid shift during spaceflight results in increased choroidal and retinal thickness. These data suggest that altered venous hemodynamics during spaceflight may contribute to SANS.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.

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