Persistent Globe Flattening in Astronauts following Long-Duration Spaceflight

Mader, Thomas H.; Gibson, Charles R.; Barratt, Michael R.; Miller, Neil R.; Subramanian, Prem S.; Killer, Hanspeter E.; Tarver, William J.; Sargsyan, Ashot E.; Garcia, Kathleen; Hart, Stephen F.; Kramer, Larry A.; Riascos, Roy; Brunstetter, Tyson; Lipsky, William; Wostyn, Peter; Lee, Andrew G.

doi:10.1080/01658107.2020.1791189

Cited by 28 publications

(29 citation statements)

References 24 publications

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“…Similar processes have been postulated to be responsible for the optic disc swelling and other ocular manifestations that occur in astronauts with ‘Spaceflight-Associated Neuro-ocular Syndrome’. 25 …”

Section: Discussionmentioning

confidence: 99%

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Elevated perioptic lipocalin-type prostaglandin D synthase concentration in patients with idiopathic intracranial hypertension

Pircher

Montali

Berberat

et al. 2022

Brain Communications

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The pathophysiology of vision loss and loss of visual field in patients with idiopathic intracranial hypertension with papilledema is not fully understood. Although elevated cerebrospinal fluid pressure induces damage to the optic nerve due to stasis of axoplasmic flow, there is no clear relationship between the severity of papilledema and CSF pressure. Furthermore, there are cases of purely unilateral papilledema and cases without papilledema despite significantly elevated intracranial pressure as well as papilledema that can persist despite a successfully lowered intracranial pressure. We hypothesize that at least in some of such cases, in addition to purely pressure-induced damage to the optic nerve, the biochemical composition of the CSF in subarachnoid space surrounding the orbital optic nerve may play a role in the pathogenesis of vision loss. In this retrospective study, we report on lipocalin-type prostaglandin D synthase concentrations in the CSF within the perioptic and lumbar subarachnoid space in 14 patients with idiopathic intracranial hypertension (13 females, mean age 45 ± 13 years) with chronic persistent papilledema resistant to maximum-tolerated medical therapy and visual impairment. CSF was collected from the subarachnoid space of the optic nerve during optic nerve sheath fenestration and from the lumbar subarachnoid space at the time of lumbar puncture. CSF was analyzed for lipocalin-type prostaglandin D synthase, and the concentrations compared between the two sites using nephelometry. Mean lipocalin-type prostaglandin D synthase concentration in the perioptic subarachnoid space was significantly higher compared with the concentration in the lumbar subarachnoid space (69 ± 51 mg/l without correction of serum contamination and 89 ± 67 mg/l after correction of serum contamination vs. 23 ± 8 mg/l; P <0.0001, Mann-Whitney U-Test). These measurements demonstrate a change and imbalance in the biochemical environment of the optic nerve. Its possible effect is discussed.

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Section: Discussionmentioning

confidence: 99%

“…Interestingly, persistent posterior globe flattening has been documented in several astronauts years following long-duration space flight, again suggesting that toxic chemicals may cause permanent sclera remodelling. 25 …”

Section: Discussionmentioning

confidence: 99%

Elevated perioptic lipocalin-type prostaglandin D synthase concentration in patients with idiopathic intracranial hypertension

Pircher

Montali

Berberat

et al. 2022

Brain Communications

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“…Mader et al subjectively identified globe flattening and optic disc oedema in 5 of the 7 astronauts they assessed, and identified thickening of the retinal nerve fibre layer in 6 of 7 astronauts [4]. In 3 of these 7 astronauts, globe flattening persisted for at least 7 years following spaceflight [19]. A 2017 case report described an astronaut who developed asymmetric optic disc oedema during spaceflight, which remained unresolved 630 days after flight [18].…”

Section: Discussionmentioning

confidence: 99%

Automated MRI-based quantification of posterior ocular globe flattening and recovery after long-duration spaceflight

Sater

Sass

Rohr

et al. 2021

Eye

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Background/Objectives Spaceflight associated neuro-ocular syndrome (SANS), a health risk related to long-duration spaceflight, is hypothesized to result from a headward fluid shift that occurs with the loss of hydrostatic pressure gradients in weightlessness. Shifts in the vascular and cerebrospinal fluid compartments alter the mechanical forces at the posterior eye and lead to flattening of the posterior ocular globe. The goal of the present study was to develop a method to quantify globe flattening observed by magnetic resonance imaging after spaceflight. Subjects/Methods Volumetric displacement of the posterior globe was quantified in 10 astronauts at 5 time points after spaceflight missions of ~6 months. Results Mean globe volumetric displacement was 9.88 mm3 (95% CI 4.56–15.19 mm3, p < 0.001) on the first day of assessment after the mission (R[return]+ 1 day); 9.00 mm3 (95% CI 3.73–14.27 mm3, p = 0.001) at R + 30 days; 6.53 mm3 (95% CI 1.24–11.83 mm3, p < 0.05) at R + 90 days; 4.45 mm3 (95% CI −0.96 to 9.86 mm3, p = 0.12) at R + 180 days; and 7.21 mm3 (95% CI 1.82–12.60 mm3, p < 0.01) at R + 360 days. Conclusions There was a consistent inward displacement of the globe at the optic nerve, which had only partially resolved 1 year after landing. More pronounced globe flattening has been observed in previous studies of astronauts; however, those observations lacked quantitative measures and were subjective in nature. The novel automated method described here allows for detailed quantification of structural changes in the posterior globe that may lead to an improved understanding of SANS.

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“…This review examined 13 studies that measured ONSD for the evaluation of the effects of microgravity or its analogs. Of those, 7 studies evaluated astronauts subjected to microgravity 1,11,[13][14][15][16][17] , and 6 only evaluated subjects examined in various ground-based analogs designed to replicate certain aspects of microgravity [18][19][20][21][22][23] , with one study using both astronauts and ground-based analogs 17 . In the studies we examined, 6 measured ONSD using US [17][18][19][21][22][23] , 6 used MRI 1,11,13,14,16,20 , and one used both methods 15 .…”

Section: Review Review Methodology and Overviewmentioning

confidence: 99%

Optic nerve sheath diameter and spaceflight: defining shortcomings and future directions

et al. 2022

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Neuro-ocular changes during long-duration space flight are known as spaceflight-associated neuro-ocular syndrome (SANS). The ability to detect, monitor, and prevent SANS is a priority of current space medicine research efforts. Optic nerve sheath diameter (ONSD) measurement has been used both terrestrially and in microgravity as a proxy for measurements of elevated intracranial pressure. ONSD shows promise as a potential method of identifying and quantitating neuro-ocular changes during space flight. This review examines 13 studies measuring ONSD and its relationship to microgravity exposure or ground-based analogs, including head-down tilt, dry immersion, or animal models. The goal of this correspondence is to describe heterogeneity in the use of ONSD in the current SANS literature and make recommendations to reduce heterogeneity in future studies through standardization of imaging modalities, measurement techniques, and other aspects of study design.

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Persistent Globe Flattening in Astronauts following Long-Duration Spaceflight

Cited by 28 publications

References 24 publications

Elevated perioptic lipocalin-type prostaglandin D synthase concentration in patients with idiopathic intracranial hypertension

Elevated perioptic lipocalin-type prostaglandin D synthase concentration in patients with idiopathic intracranial hypertension

Automated MRI-based quantification of posterior ocular globe flattening and recovery after long-duration spaceflight

Optic nerve sheath diameter and spaceflight: defining shortcomings and future directions

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