PMID- 27236645
OWN - NLM
STAT- MEDLINE
DCOM- 20180126
LR  - 20181202
IS  - 1617-7940 (Electronic)
IS  - 1617-7940 (Linking)
VI  - 16
IP  - 1
DP  - 2017 Feb
TI  - Characterization of the mechanical behavior of the optic nerve sheath and its 
      role in spaceflight-induced ophthalmic changes.
PG  - 33-43
LID - 10.1007/s10237-016-0800-7 [doi]
AB  - Visual impairment and intracranial pressure (VIIP) syndrome is characterized by a 
      number of permanent ophthalmic changes, including loss of visual function. It 
      occurs in some astronauts during long-duration spaceflight missions. Thus, 
      understanding the pathophysiology of VIIP is currently a major priority in space 
      medicine research. It is hypothesized that maladaptive remodeling of the optic 
      nerve sheath (ONS), in response to microgravity-induced elevations in 
      intracranial pressure (ICP), contributes to VIIP. However, little is known about 
      ONS biomechanics. In this study, we developed a custom mechanical testing system 
      that allowed for unconfined lengthening, twisting, and circumferential distension 
      of the porcine ONS during inflation and axial loading. Data were fit to a 
      four-fiber family constitutive equation to extract material and structural 
      parameters. Inflation testing showed a characteristic "cross-over point" in the 
      pressure-diameter curves under different axial loads in all samples that were 
      tested; the cross-over pressure was [Formula: see text] mmHg ([Formula: see 
      text]). Large sample-to-sample variations were observed in the circumferential 
      strain, while only modest variations were observed in the circumferential stress. 
      Multiphoton microscopy revealed that the collagen fibers of the ONS were 
      primarily oriented axially when the tissue was loaded. The existence of this 
      cross-over behavior is expected to be neuroprotective, as it would avoid optic 
      nerve compression during routine changes in gaze angle, so long as ICP was within 
      the normal range. Including these observations into computational models of VIIP 
      will help provide insight into the pathophysiology of VIIP and could help 
      identify risk factors and potential interventions.
FAU - Raykin, Julia
AU  - Raykin J
AD  - Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of 
      Technology and Emory University, 315 Ferst Dr. NW, Atlanta, GA, 30332, USA.
FAU - Forte, Taylor E
AU  - Forte TE
AD  - Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of 
      Technology and Emory University, 315 Ferst Dr. NW, Atlanta, GA, 30332, USA.
FAU - Wang, Roy
AU  - Wang R
AD  - Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of 
      Technology and Emory University, 315 Ferst Dr. NW, Atlanta, GA, 30332, USA.
FAU - Feola, Andrew
AU  - Feola A
AD  - Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of 
      Technology and Emory University, 315 Ferst Dr. NW, Atlanta, GA, 30332, USA.
FAU - Samuels, Brian C
AU  - Samuels BC
AD  - Department of Ophthalmology, University of Alabama at Birmingham, Birmingham, AL, 
      USA.
FAU - Myers, Jerry G
AU  - Myers JG
AD  - NASA Glenn Research Center, Cleveland, OH, USA.
FAU - Mulugeta, Lealem
AU  - Mulugeta L
AD  - Universities Space Research Association, Houston, TX, USA.
FAU - Nelson, Emily S
AU  - Nelson ES
AD  - NASA Glenn Research Center, Cleveland, OH, USA.
FAU - Gleason, Rudy L
AU  - Gleason RL
AD  - Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of 
      Technology and Emory University, 315 Ferst Dr. NW, Atlanta, GA, 30332, USA.
AD  - George W. Woodruff School of Mechanical Engineering, Georgia Institute of 
      Technology, Atlanta, GA, USA.
FAU - Ethier, C Ross
AU  - Ethier CR
AD  - Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of 
      Technology and Emory University, 315 Ferst Dr. NW, Atlanta, GA, 30332, USA. 
      ross.ethier@bme.gatech.edu.
AD  - George W. Woodruff School of Mechanical Engineering, Georgia Institute of 
      Technology, Atlanta, GA, USA. ross.ethier@bme.gatech.edu.
LA  - eng
PT  - Journal Article
DEP - 20160528
PL  - Germany
TA  - Biomech Model Mechanobiol
JT  - Biomechanics and modeling in mechanobiology
JID - 101135325
SB  - IM
MH  - Animals
MH  - *Biomechanical Phenomena
MH  - Humans
MH  - Intracranial Pressure/*physiology
MH  - Models, Biological
MH  - Optic Nerve/*physiology
MH  - *Space Flight
MH  - Swine
OTO - NOTNLM
OT  - Biosolid mechanics
OT  - Constitutive model
OT  - Intracranial pressure
OT  - Optic nerve sheath
OT  - Spaceflight physiology
OT  - VIIP
EDAT- 2016/05/30 06:00
MHDA- 2018/01/27 06:00
CRDT- 2016/05/30 06:00
PHST- 2015/12/01 00:00 [received]
PHST- 2016/05/17 00:00 [accepted]
PHST- 2016/05/30 06:00 [pubmed]
PHST- 2018/01/27 06:00 [medline]
PHST- 2016/05/30 06:00 [entrez]
AID - 10.1007/s10237-016-0800-7 [pii]
AID - 10.1007/s10237-016-0800-7 [doi]
PST - ppublish
SO  - Biomech Model Mechanobiol. 2017 Feb;16(1):33-43. doi: 10.1007/s10237-016-0800-7. 
      Epub 2016 May 28.