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Athletic development specialists dedicated to the art and science of excellence in movement

Vision Limitations and Gaze Compensation

Vision is without a doubt one of the most underappreciated aspects of movement.  Unfortunately, we assume more about vision than we assume about other performance domains.  To measure vision strictly in terms of 20-20 is like evaluating movement only with single joint range-of-motion and isolated muscle strength.  It’s obvious that range-of-motion is simply one physical measure and with limited predictive value for performance.  Despite this obvious limitation in the musculoskeletal realm, we often assume that someone has functional vision merely because they are 20-20 or have corrective lenses to get them there. 

One area to help understand this concept is by studying vision loss.  If someone moves poorly, particularly in a multidirectional sport, their dysfunctional movements may actually reflect their brain’s best available strategy to deal with vision limitations.  Just close your eyes and run around if you don’t believe me.  Quite simply, everyone “gazes” differently, just as everyone has individual musculoskeletal movement patterns.  These musculoskeletal movement patterns are expressions of what the eyes can see and the brain can process. 

A recent study by Wiecek (2012) highlights this concept.  Authors studied 10 subjects with peripheral vision field loss and 13 without this limitation.  Subjects were given a series of gaze tests to search for objects within various visual fields, some of which occurred outside the sighted area for the patients.  Although, there were no significant differences in the number of searches and search duration, the patients demonstrated “a biased directional distribution that was not directly related to the locus of vision loss, challenging feed-forward models of eye movement control. Consequently, many patients do not optimally compensate for visual field loss during visual search.” 

What this means: with vision impairments, the brain has not been properly educated to deal with the impairment.  (“visual field defects may not only hinder vision by limiting what the subject sees of the environment but also by limiting the visual system's ability to program efficient eye movements.” (Cornelisson 2005)  This is yet additional evidence why visual training, even if not formally done with vision therapy (which can be expensive), must at least be incorporated into daily movement practice.  Vision training can be as simple as cueing proper gaze mechanics or with disassociation tasks.   

The interaction of locomotion and visual movement patterns is referred to as optic flow (Pinheiro Menuchi 2012).  When a critical part of vision is altered, the body will compensate in some way.  If these compensations become habitual, it may expose athletes to injury, or impair performance depending on how the nervous system reacts.  As the Wiecek study shows, compensations are often inadequate and random relative to the specific impairment.

References

Wiecek E, Pasquale LRFiser J, Dakin S, Bex PJ.  Effects of peripheral visual field loss on eye movements during visual search. Front Psychol. 2012;3:472. doi: 10.3389/fpsyg.2012.00472. Epub 2012 Nov 5.

Pinheiro Menuchi M RT, Bucken Gobbi LT.  Optic flow contribution to locomotion adjustments in obstacle avoidance.  Motor Control. 2012 Oct;16(4):506-20.

Cornelissen FW, Bruin KJ, Kooijman AC.  The influence of artificial scotomas on eye movements during visual search.  Optom Vis Sci. 2005 Jan;82(1):27-35.

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