Visual control of foot placement when walking over complex terrain.

2014 ◽  
Vol 40 (1) ◽  
pp. 106-115 ◽  
Author(s):  
Jonathan S. Matthis ◽  
Brett R. Fajen
Keyword(s):  
Complex Terrain ◽  
Visual Control ◽  
Foot Placement

scholarly journals Visual control of precise foot placement when walking over complex terrain

2013 ◽  
Vol 13 (9) ◽  
pp. 121-121 ◽  
Author(s):  
J. Matthis ◽  
S. Barton ◽  
B. Fajen
Keyword(s):  
Complex Terrain ◽  
Visual Control ◽  
Foot Placement

scholarly journals Visual control of foot placement when walking over rough terrain

2011 ◽  
Vol 11 (11) ◽  
pp. 915-915 ◽  
Author(s):  
J. Matthis ◽  
B. Fajen
Keyword(s):  
Visual Control ◽  
Rough Terrain ◽  
Foot Placement

scholarly journals The critical phase for visual control of human walking over complex terrain

2017 ◽  
Vol 114 (32) ◽  
pp. E6720-E6729 ◽  
Author(s):  
Jonathan Samir Matthis ◽  
Sean L. Barton ◽  
Brett R. Fajen
Keyword(s):  
Complex Terrain ◽  
Visual Information ◽  
Center Of Mass ◽  
Ground Surface ◽  
The Body ◽  
Foot Placement ◽  
Preceding Step ◽  
Control Work ◽  
Base Of Support ◽  
Target Visibility

To walk efficiently over complex terrain, humans must use vision to tailor their gait to the upcoming ground surface without interfering with the exploitation of passive mechanical forces. We propose that walkers use visual information to initialize the mechanical state of the body before the beginning of each step so the resulting ballistic trajectory of the walker’s center-of-mass will facilitate stepping on target footholds. Using a precision stepping task and synchronizing target visibility to the gait cycle, we empirically validated two predictions derived from this strategy: (1) Walkers must have information about upcoming footholds during the second half of the preceding step, and (2) foot placement is guided by information about the position of the target foothold relative to the preceding base of support. We conclude that active and passive modes of control work synergistically to allow walkers to negotiate complex terrain with efficiency, stability, and precision.

scholarly journals The visual control of walking over complex terrain with flat versus raised obstacles

2017 ◽  
Vol 17 (10) ◽  
pp. 707
Author(s):  
Sean Barton ◽  
Scott Steinmetz ◽  
Gabe Diaz ◽  
Jonathan Matthis ◽  
Brett Fajen
Keyword(s):  
Complex Terrain ◽  
Visual Control

Transscleral Extraction of an Intraocular Foreign Body From the Posterior Segment of the Eye Without Pars Plana Vitrectomy

2020 ◽  
Vol 76 (1) ◽  
pp. 14-23
Author(s):  
Štěpán Rusňák ◽  
Lenka Hecová
Keyword(s):  
Foreign Body ◽  
Pars Plana Vitrectomy ◽  
Young Patients ◽  
Vitreous Body ◽  
Visual Control ◽  
Intraocular Foreign Body ◽  
Survey Study ◽  
Surgical Method ◽  
Eye Trauma ◽  
Pars Plana

Purpose: Penetrating eye trauma with an intraocular foreign body is very frequent, especially in men in their productive age. Pars plana vitrectomy would be the standard surgical method at our department. However, in indicated cases (metallic intraocular bodies in the posterior eye segment in young patients with well transparent ocular media without detached ZSM and without any evident vitreoretinal traction) transscleral extraction of the intraocular foreign body is performed using the exo magnet, eventually endo magnet with a minimal PPV without PVD induction under the visual control of endo-illumination. Materials and Methods: Between June 2003 and June 2018, 66 eyes of 66 patients diagnosed with a penetrating eye trauma caused by an intraocular foreign body located in the posterior eye segment were treated. In 18 eyes (27,3 %) with a metallic foreign body in vitreous (body) or in retina, no PPV or a minimal PPV without PVD was used as a surgical method. In the remaining 48 eyes (72,7 %), a standard 20G, respectively 23G PPV method were used together with PVD induction and the foreign body extraction via endo or exo magnet. Conclusions: As demonstrated by our survey/study, in the cases of a thoroughly considered indication an experimented vitreoretinal surgeon can perform a safe NCT transscleral extraction from the posterior eye segment via exo magnet, eventually endo magnet under the visual control of a contact display system with a minimal PPV. Thereby, the surgeon can enhance the patient´s chance to preserve their own lens and its accommodative abilities as well as reduce the risk of further surgical interventions of the afflicted eye.

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