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Review
. 2020 Feb 7:6:7.
doi: 10.1038/s41526-020-0097-9. eCollection 2020.

Spaceflight associated neuro-ocular syndrome (SANS) and the neuro-ophthalmologic effects of microgravity: a review and an update

Andrew G Lee  1   2   3   4   5   6 , Thomas H Mader  7 , C Robert Gibson  8 , William Tarver  9 , Pejman Rabiei  10 , Roy F Riascos  10 , Laura A Galdamez  11 , Tyson Brunstetter  12
Affiliations
Review

Spaceflight associated neuro-ocular syndrome (SANS) and the neuro-ophthalmologic effects of microgravity: a review and an update

Andrew G Lee et al. NPJ Microgravity. .

Erratum in

Abstract

Prolonged microgravity exposure during long-duration spaceflight (LDSF) produces unusual physiologic and pathologic neuro-ophthalmic findings in astronauts. These microgravity associated findings collectively define the "Spaceflight Associated Neuro-ocular Syndrome" (SANS). We compare and contrast prior published work on SANS by the National Aeronautics and Space Administration's (NASA) Space Medicine Operations Division with retrospective and prospective studies from other research groups. In this manuscript, we update and review the clinical manifestations of SANS including: unilateral and bilateral optic disc edema, globe flattening, choroidal and retinal folds, hyperopic refractive error shifts, and focal areas of ischemic retina (i.e., cotton wool spots). We also discuss the knowledge gaps for in-flight and terrestrial human research including potential countermeasures for future study. We recommend that NASA and its research partners continue to study SANS in preparation for future longer duration manned space missions.

Keywords: Eye manifestations; Medical research; Physical examination.

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Conflict of interest statement

Competing interestsAll of the authors declare that they have no “competing interests” related to funding, person, or financial interest. Although the authors work directly (W.T., T.B.) as employees or indirectly as consultants (A.G.L., C.R.G.) for NASA, the views and opinions expressed here are those of the authors and do not necessarily reflect the views of NASA or the United States government. Dr. Lee has served as treating physician and expert witness but no cases involved Space Flight associated Neuro-ocular syndrome (SANS) or any of the content of this paper. In addition, the remaining authors do not have any of the following non-financial interests: Unpaid membership in a government or non-governmental organization; unpaid membership in an advocacy or lobbying organization; unpaid advisory position in a commercial organization; Writing or consulting for an educational company; or Acting as an expert witness.

Figures

Fig. 1
Fig. 1. Bruch membrane opening (BMO) and height.
a Marking of the BMO (orange marker) is shown on 1 radial section through the optic nerve head. The BMO center (red dashed line) was used to determine the location for a reference plane at 2 mm (white line), from which the BMO height was quantified (blue line). b The BMO height is recessed in pre-flight optical coherence tomographic (OCT) scans compared with healthy controls. This difference increases after long-duration microgravity exposure. It should be noted that most astronauts included in this study had previous spaceflight experience. (Reprinted with permission from Patel et al.87).
Fig. 2
Fig. 2. Post-flight imaging of the right eye.
a Fundus imaging showing the “C” halo of the Frisén Grade 1 disc edema and choroidal folds inferior to the disc. b Scanning laser ophthalmoscopy (SLO) image from the SD-OCT with an overlay of the vertical raster scan placement. Note the choroidal folds superior and inferior to the disc visible in the SLO image. c The retinal cross-section obtained by the vertical scan just nasal to the disc showing retinal nerve fiber layer thickening and severe choroidal folds. (Reprinted with permission from Patel et al.87).
Fig. 3
Fig. 3
Prior optical coherence tomography (OCT) scanning protocol for SANS.
Fig. 4
Fig. 4
Current OCT2 scanning protocols for SANS.
See this image and copyright information in PMC

References

    1. Mader TH, et al. Optic disc edema, globe flattening, choroidal folds, and hyperopic shifts observed in astronauts after long-duration space flight. Ophthalmology. 2011;118:2058–2069. doi: 10.1016/j.ophtha.2011.06.021. - DOI - PubMed
    1. Lee AG, et al. Neuro-ophthalmology of space flight. J. Neuroophthalmol. 2016;36:85–91. doi: 10.1097/WNO.0000000000000334. - DOI - PubMed
    1. Mader TH, Gibson CR, Lee AG. Choroidal folds in astronauts. Invest Ophthalmol. Vis. Sci. 2016;57:592. doi: 10.1167/iovs.15-18720. - DOI - PubMed
    1. Mader TH, Gibson CR, Hart SF, Lee AG. Asymmetric papilledema in idiopathic intracranial hypertension. J. Neuroophthalmol. 2016;36:111–112. doi: 10.1097/WNO.0000000000000363. - DOI - PubMed
    1. Mader TH, et al. Persistent asymmetric optic disc swelling after long-duration space flight: Implications for pathogenesis. J. Neuroophthalmol. 2017;37:133–139. doi: 10.1097/WNO.0000000000000467. - DOI - PubMed