The escape of retrobulbar cerebrospinal fluid in the astronaut’s eye: mission impossible?

Wostyn, Peter; Mader, Thomas H.; Gibson, Charles R.; Killer, Hanspeter E.

doi:10.1038/s41433-019-0453-8

Cited by 23 publications

(18 citation statements)

References 34 publications

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“…We hypothesized that astronauts with less-compliant optic nerve sheaths may be more likely to develop optic disc swelling, given that a greater degree of optic nerve sheath rigidity that prevents further expansion may result in more CSF pressure increase in the subarachnoid space surrounding the optic nerve (2, 3). According to this hypothesis, microgravity-induced ocular changes may be partially determined by the elastic properties of the optic nerve sheath (4). As such, it would be interesting to evaluate the optic nerve sheath response to alterations in CSF pressure as a predictive biomarker for optic disc edema in astronauts (2).…”

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confidence: 99%

The buffering capacity of the brain and optic nerve against spaceflight-associated neuro-ocular syndrome

Wostyn¹,

Mader

Gibson

et al. 2019

Proc. Natl. Acad. Sci. U.S.A.

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confidence: 99%

The buffering capacity of the brain and optic nerve against spaceflight-associated neuro-ocular syndrome

Wostyn¹,

Mader

Gibson

et al. 2019

Proc. Natl. Acad. Sci. U.S.A.

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“…The ventricular volume decreased after 7 months post mission but did not return to baseline. Greater lateral ventricular volume increase was also correlated with visual acuity loss Evidence of CSF compartment enlargement related to LDSF and suggests possible role for this in SANS Wostyn 25 et al 2019 Review of select peer-reviewed articles regarding the pathophysiology of SANS ONH edema in astronauts may at least in part result from forcing of perioptic CSF into the ONH along perivascular spaces surrounding the central retinal vessels, related to long-standing microgravity fluid shifts and variations in optic nerve sheath anatomy and compliance. Supports the cephalad fluid shift theory for the pathophysiology of SANS Elwy 26 et al 2020 Review of 19 studies evaluating the role of raised ICP in SANS 8/11 studies found significant increase in ICP after HDT, 3 also showed associated increase in IOP.…”

Section: Resultsmentioning

confidence: 91%

“…They also noted that after 150 days of microgravity exposure, choroidal thickness and TRT increased by 50 μm and 26 μm, respectively. Wostyn et al 25 reviewed multiple papers regarding the cephalad fluid shift and reported that optic nerve head (ONH) edema may at least in part result from the forcing of perioptic CSF into the ONH along perivascular spaces. Gerlach et al 6 reported that on imaging of the optic nerves of healthy volunteers who underwent head down tilt (HDT) for 4.5 hours, fractional anisotropy and axial diffusivity were significantly increased, suggesting increased CSF volume and movement within the optic nerve sheath.…”

Section: Resultsmentioning

confidence: 99%

<p>Spaceflight Associated Neuro-Ocular Syndrome (SANS): A Systematic Review and Future Directions</p>

Paez¹,

Mudie²,

Subramanian³

2020

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Purpose: To present a systematic review of the current body of literature surrounding spaceflight associated neuro-ocular syndrome (SANS) and highlight priorities for future research. Methods: Three major biomedical databases were searched with the following terms: ((neuro ocular) OR ((brain) AND (eye))) AND ((spaceflight) OR (astronaut) OR (microgravity)) AND (ENGLISH[Language]). Once duplicates were removed, 283 papers were left. Articles were excluded if they were not written in English or conference abstracts only. We avoided including review papers which did not provide any new information; however, two reviews on the pathophysiology of SANS were included for completeness. No limitations on date of publication were used. All included entries were then summarized for their contribution to knowledge about SANS. Results: Four main themes among the publications emerged: papers defining the clinical entity of SANS, its pathophysiology, technology used to study SANS, and publications on possible prevention of SANS. The key clinical features of SANS include optic nerve head elevation, hyperopic shifts, globe flattening, choroidal folds, and increased cerebrospinal fluid (CSF) volume in optic nerve sheaths. Two main hypotheses are proposed for the pathophysiology of SANS. The first being elevated intracranial pressure and the second compartmentalization of CSF to the globe. These hypotheses are not mutually exclusive, and our understanding of the pathophysiology of SANS is still evolving. The use of optical coherence tomography (OCT) has greatly furthered our knowledge about SANS, and with the deployment of OCT to the International Space Station, we now have ability to collect intraflight data. No effective prevention for SANS has been found, although fortunately, even with persistent anatomic and physiologic neuro-ocular changes, any functional impact has been correctable with spectacles. Conclusion: This is the first systematic review of SANS. Despite the limitations of studying a syndrome that can only occur in a small, discrete population, we present a thorough overview of the literature surrounding SANS and several key areas important for future research are identified.

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“…Microgravity is not the only change of circumstance for the cells. Microgravity fluid shift was also believed to exert significant changes in eyes during and after long-duration spaceflight ( Wostyn et al, 2019 ). Therefore, in vivo and long-term studies under stimulated microgravity and in real spaceflight should be carried out.…”

Section: Discussionmentioning

confidence: 99%

Effects of Simulated Microgravity on Ultrastructure and Apoptosis of Choroidal Vascular Endothelial Cells

Zhao

Shi²,

Qiu³

et al. 2021

Front. Physiol.

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BackgroundIt was confirmed that simulated microgravity (SMG) led to ultrastructural alterations and apoptosis in many types of microvascular endothelial cells. However, whether SMG would also affect choroidal vascular endothelial cells (CVECs) remains unknown. This study was designed to investigate the effects of SMG on ultrastructure and apoptosis of CVECs.MethodsThe rotary cell culture system (RCCS) was utilized to simulate microgravity condition. Human CVECs were cultured under normal gravity (NG) or SMG condition for 3 days. The ultrastructure was viewed under transmission electron microscopy, and the organization of F-actin was observed by immunofluorescence staining. Additionally, the apoptosis percentage was calculated using flow cytometry. Moreover, the mRNA and protein expression of BAX, Bcl-2, Caspase3, Cytochrome C, p-AKT, and p-PI3K were detected with quantitative PCR and Western blot at different exposure time.ResultsIn the SMG group, CVECs presented with a shrunk cell body, chromatin condensation and margination, mitochondria vacuolization, and apoptotic bodies. The amount of F-actin decreased, and the filaments of F-actin were sparse or even partly discontinuous after cultivation under SMG for 72 h. The proportions of apoptotic CVECs in SMG groups at 24 and 72 h were significantly higher than those in the NG group (P < 0.001). The mRNA and protein expression of Bax, Caspase3, and Cytochrome C of CVECs in SMG groups at 24 and 72 h significantly increased than those of the NG group, respectively (P < 0.001). The alterations of p-AKT and p-PI3K protein expression possessed similar trends. On the contrary, the mRNA and protein expression of Bcl-2 in CVECs under SMG at 24 and 72 h were significantly less than that of the NG group, respectively (P < 0.001).ConclusionSimulated microgravity conditions can lead the alterations of the F-actin structure and apoptosis of CVECs. The Bcl-2 apoptosis pathway and PI3K/AKT pathway may participate in the damage of CVECs caused by SMG.

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The escape of retrobulbar cerebrospinal fluid in the astronaut’s eye: mission impossible?

Cited by 23 publications

References 34 publications

The buffering capacity of the brain and optic nerve against spaceflight-associated neuro-ocular syndrome

The buffering capacity of the brain and optic nerve against spaceflight-associated neuro-ocular syndrome

<p>Spaceflight Associated Neuro-Ocular Syndrome (SANS): A Systematic Review and Future Directions</p>

Effects of Simulated Microgravity on Ultrastructure and Apoptosis of Choroidal Vascular Endothelial Cells

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