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Wostyn P, Gibson CR, Mader TH. The odyssey of the ocular and cerebrospinal fluids during a mission to Mars: the "ocular glymphatic system" under pressure. Eye (Lond) 2022; 36:686-691. [PMID: 34373611 PMCID: PMC8956714 DOI: 10.1038/s41433-021-01721-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 07/10/2021] [Accepted: 07/26/2021] [Indexed: 02/07/2023] Open
Abstract
A significant proportion of the astronauts who spend extended periods in microgravity develop ophthalmic abnormalities including optic disc edema, globe flattening, chorioretinal folds, and hyperopic refractive error shifts. A constellation of these neuro-ophthalmic findings has been termed "spaceflight-associated neuro-ocular syndrome". Understanding this syndrome is currently a top priority for NASA, especially in view of future long-duration missions (e.g., Mars missions). The recent discovery of an "ocular glymphatic system" can potentially help to unlock mechanisms underlying microgravity-induced optic disc edema. Indeed, a major paradigm shift is currently occurring in our understanding of transport of fluids and solutes through the optic nerve following the recent discovery of an optic nerve glymphatic pathway for influx of cerebrospinal fluid. In addition, the recent identification of an entirely new glymphatic pathway for efflux of ocular fluid may have profound implications for fluid dynamics in the eye. Observations pertaining to this ocular glymphatic pathway provide critical new insights into how intracranial pressure can alter basic fluid transport in the eye. We believe that these novel findings have the potential to be game changers in our understanding of the pathogenesis of optic disc edema in astronauts. In the present review, we integrate these new insights with findings on the intracranial and neuro-ophthalmologic effects of microgravity in one coherent conceptual framework. Further studies in this area of investigation could not only provide exciting new insights into the mechanisms underlying microgravity-induced optic disc edema but also offer opportunities to develop countermeasure strategies.
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Affiliation(s)
- Peter Wostyn
- Department of Psychiatry, PC Sint-Amandus, Beernem, Belgium
| | - Charles Robert Gibson
- Coastal Eye Associates, Webster, TX USA ,grid.481680.30000 0004 0634 8729KBR, NASA Space Medicine Operations Division, Houston, TX USA
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2
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Özelbaykal B, Öğretmenoğlu G, Gedik Ş. The Effects of Space Radiation and Microgravity on Ocular Structures. Turk J Ophthalmol 2022; 52:57-63. [PMID: 35196841 PMCID: PMC8876783 DOI: 10.4274/tjo.galenos.2021.29566] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Long-term exposure to microgravity and space radiation leads to physiological and pathological changes in human biology. Pathological neuro-ocular changes are collected under the name spaceflight-associated neuro-ocular syndrome. This review examines studies on the effects of microgravity and space radiation on the ocular structures and their results. In addition, we discuss treatment methods and hypotheses to reduce the effects of microgravity and space radiation on biological structures.
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Affiliation(s)
| | - Gökhan Öğretmenoğlu
- Adana City Training and Research Hospital, Clinic of Ophthalmology, Adana, Turkey
| | - Şansal Gedik
- Selçuk University Faculty of Medicine, Department of Ophthalmology, Konya, Turkey
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3
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van de Beeten SDC, Ramdas WD, Yang S, Loudon SE, den Ottelander BK, Rizopoulos D, van Veelen MLC, Mathijssen IMJ. The use of OCT to detect signs of intracranial hypertension in patients with sagittal suture synostosis: Reference values and correlations. Childs Nerv Syst 2022; 38:1937-1947. [PMID: 35972534 PMCID: PMC9522733 DOI: 10.1007/s00381-022-05598-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Accepted: 07/01/2022] [Indexed: 11/28/2022]
Abstract
PURPOSE To obtain pediatric normative reference values and determine whether optical coherence tomography (OCT) corresponds better with clinical signs of intracranial hypertension (ICH) compared to the traditional screening method fundoscopy in a large cohort of one type of single suture craniosynostosis. METHODS Control subjects without optic nerve diseases and isolated sagittal synostosis patients aged 3-10 years who underwent fundoscopy and OCT were included in this prospective cohort study. Normative reference values were obtained through bootstrap analysis. Main outcome was the association between peripapillary total retinal thickness (TRT) and total retinal volume (TRV) and appearance on fundoscopy. Signs and symptoms suggestive of ICH, including skull growth arrest, fingerprinting, and headache, were scored. RESULTS Sixty-four healthy controls and 93 isolated sagittal synostosis patients were included. Normative cut-off values for mean TRT are < 256 μm and > 504 μm and for mean TRV < 0.21 mm3 and > 0.39 mm3. TRT was increased in 16 (17%) and TRV in 15 (16%) of 93 patients, compared to only 4 patients with papilledema on fundoscopy (4%). Both parameters were associated with papilledema on fundoscopy (OR = 16.7, p = 0.02, and OR = 18.2, p = 0.01). Skull growth arrest was significantly associated with abnormal OCT parameters (OR = 13.65, p < 0.01). CONCLUSIONS The established cut-off points can be applied to screen for ICH in pediatrics. The present study detected abnormalities with OCT more frequent than with fundoscopy, which were associated with skull growth arrest. Therefore, a combination of OCT, fundoscopy, and skull growth arrest can improve clinical decision-making in craniosynostosis.
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Affiliation(s)
- Stephanie D C van de Beeten
- Dutch Craniofacial Center, Department of Plastic and Reconstructive Surgery and Hand Surgery, Erasmus MC-Sophia Children's Hospital, University Medical Center Rotterdam, Room EE-1591, Postbus 2040, 3000 CA, Wytemaweg 80, 2015 CN, Rotterdam, The Netherlands.
| | - Wishal D Ramdas
- Department of Ophthalmology, Erasmus MC-Sophia Children's Hospital, University Medical Center Rotterdam, Postbus 2040, 3000 CA, Rotterdam, The Netherlands
| | - Sumin Yang
- Dutch Craniofacial Center, Department of Plastic and Reconstructive Surgery and Hand Surgery, Erasmus MC-Sophia Children's Hospital, University Medical Center Rotterdam, Room EE-1591, Postbus 2040, 3000 CA, Wytemaweg 80, 2015 CN, Rotterdam, The Netherlands
| | - Sjoukje E Loudon
- Department of Ophthalmology, Erasmus MC-Sophia Children's Hospital, University Medical Center Rotterdam, Postbus 2040, 3000 CA, Rotterdam, The Netherlands
| | - Bianca K den Ottelander
- Dutch Craniofacial Center, Department of Plastic and Reconstructive Surgery and Hand Surgery, Erasmus MC-Sophia Children's Hospital, University Medical Center Rotterdam, Room EE-1591, Postbus 2040, 3000 CA, Wytemaweg 80, 2015 CN, Rotterdam, The Netherlands
| | - Dimitris Rizopoulos
- Department of Biostatistics, Erasmus MC, University Medical Center Rotterdam, Postbus 2040, 3000 CA, Rotterdam, The Netherlands
| | - Marie-Lise C van Veelen
- Department of Neurosurgery, Erasmus MC-Sophia Children's Hospital, University Medical Center Rotterdam, Room SK-1204, Postbus 2040, 3000 CA, Rotterdam, The Netherlands
| | - Irene M J Mathijssen
- Dutch Craniofacial Center, Department of Plastic and Reconstructive Surgery and Hand Surgery, Erasmus MC-Sophia Children's Hospital, University Medical Center Rotterdam, Room EE-1591, Postbus 2040, 3000 CA, Wytemaweg 80, 2015 CN, Rotterdam, The Netherlands
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Spaceflight associated neuro-ocular syndrome (SANS) and the neuro-ophthalmologic effects of microgravity: a review and an update. NPJ Microgravity 2020; 6:7. [PMID: 32047839 PMCID: PMC7005826 DOI: 10.1038/s41526-020-0097-9] [Citation(s) in RCA: 130] [Impact Index Per Article: 32.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 11/11/2019] [Indexed: 11/08/2022] Open
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.
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Liu KC, Fleischman D, Lee AG, Killer HE, Chen JJ, Bhatti MT. Current concepts of cerebrospinal fluid dynamics and the translaminar cribrosa pressure gradient: a paradigm of optic disk disease. Surv Ophthalmol 2020; 65:48-66. [DOI: 10.1016/j.survophthal.2019.08.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Revised: 08/07/2019] [Accepted: 08/16/2019] [Indexed: 12/11/2022]
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The buffering capacity of the brain and optic nerve against spaceflight-associated neuro-ocular syndrome. Proc Natl Acad Sci U S A 2019; 116:15770-15771. [PMID: 31363044 DOI: 10.1073/pnas.1908865116] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Lee AG, Mader TH, Gibson CR, Brunstetter TJ, Tarver WJ. Space flight-associated neuro-ocular syndrome (SANS). Eye (Lond) 2018. [PMID: 29527011 DOI: 10.1038/s41433-018-0070-y] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Interesting novel and somewhat perplexing physiologic and pathologic neuro-ocular findings have been documented in astronauts during and after long duration space flight (LDSF). These findings collectively have been termed the "space flight-associated neuro-ocular syndrome" (SANS). The National Aeronautics and Space Administration (NASA) in the United States has meticulously and prospectively documented the clinical, ultrasound, optical coherence tomography imaging, and radiographic findings of SANS including unilateral and bilateral optic disc edema, globe flattening, choroidal and retinal folds, hyperopic refractive error shifts, and nerve fiber layer infarcts (i.e., cotton wool spots). NASA and collaborating researchers continue to study SANS in preparation for future manned missions to space, including continued trips to the ISS, a return to the moon, or perhaps new voyages to the asteroid belt, or the planet, Mars.
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Affiliation(s)
- Andrew G Lee
- Department of Ophthalmology, Houston Methodist Hospital, Houston, TX, USA. .,Baylor College of Medicine, Houston, TX, USA. .,Departments of Ophthalmology, Neurology, and Neurosurgery, Weill Cornell Medical College, New York, NY, USA. .,Department of Ophthalmology, The University of Texas Medical Branch, Galveston, TX, USA. .,Department of Ophthalmology, The University of Iowa Hospitals and Clinics, Iowa City, IA, USA. .,UT MD Anderson Cancer Center, Houston, TX, USA.
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Moodley AA, Dlwati MS, Durand M. Intracanalicular Optic Nerve Swelling and Signal Change in Fulminant Untreated Idiopathic Intracranial Hypertension. Neuroophthalmology 2017; 41:84-89. [PMID: 28348630 DOI: 10.1080/01658107.2016.1258581] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Revised: 10/19/2016] [Accepted: 11/05/2016] [Indexed: 10/20/2022] Open
Abstract
The role of the optic canal in the pathogenesis of papilloedema has been under scrutiny recently. Whether a larger canal precedes more severe papilloedema or is the result of bone remodelling from chronically raised pressure across a pressure gradient is not clear. The authors present the magnetic resonance imaging findings of a 29-year-old female with fulminant and untreated idiopathic intracranial hypertension. Imaging showed focal expansion and intrinsic signal changes of the intracanalicular optic nerve. The authors discuss the possibility of either fluid accumulation within the optic nerves from a water hammer effect across blocked optic canals resulting from the steep pressure gradient or opticomalacia (optic nerve softening) from chronic ischaemia.
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Affiliation(s)
- Anand A Moodley
- Department of Neurology, Greys Hospital, Pietermaritzburg, South Africa; Department of Neurology, University of KwaZulu-Natal, Durban, South Africa
| | | | - Miranda Durand
- Department of Neurology, University of KwaZulu-Natal, Durban, South Africa; Department of Radiology, Greys Hospital, Pietermaritzburg, South Africa
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