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

The Eyes Have It: Thoughts on Vision and Its Effect on Movement and Posture

For nearly all of us, the eyes are a prime gateway to the outside world.  Despite incredible advances in ophthalmology and optometry, the connection between the visual and musculoskeletal has not been widely studied.  As a result, eye professionals, pediatricians (the first responders for many eye issues), and sports professionals tend to stay within their own separate domains.   Athletes/patients may get answers in one area but are left to fill gaps on their own.  Having dealt with both extremes from normal vision athletes through completely blind Paralympic athletes we’ve been fortunate to appreciate vision’s role in shaping movement, in part due to partnerships with vision professionals who share common philosophies on movement and development. 

The relation between the eyes and movement is simple, yet complex:  If the eyes are tilted one direction, have poor convergence, or any other dysfunctions, the head, neck, and body must adjust accordingly.  As such, common postural deviations such as a chronically lowered head, lifted chin, or lateral head tilt may reflect gaze problems.  (“Abnormal head position is adopted in order to improve visual acuity, avoid diplopia or obtain a more comfortable binocular vision. The head can be turned or tilted toward right or left, with the chin rotated up or downwards or combination of these positions.  There is nearly always a significant reason for an abnormal or compensatory head position and the patient often may adopt it unconsciously. The cause may be an ocular, muscular, skeletal or neurological disease. Very rare it may be a habit, without any reason to adopt it.” Tedorescu 2010)

Consider “dropped hip” in running, something many try to solve via mechanical interventions, whether running form training or even with orthotics.  Runners are sold countless interventions to keep the hips level, but the dropped hip may actually be a correction to equilibrate the eyes.  However, based on vision characteristics, a person may actually need to tilt their entire body to see and feel the world as level. 

It’s awfully presumptuous for coaches to say “you’re running incorrectly” without considering/ruling out factors such as vision.   “Correct” running may actually be “incorrect” given that person’s gaze pattern, along with other related factors like balance.  Throw fatigue into the equation and its potential impact on all forms of perception and narrowly applied biomechanical explanations start to break down.   Mechanics are important, but demand interpretation based on the qualities of the individual athlete.  Don't be duped by charlatans who think they have the single magic tool!

Kraft (1992) studied a five year sample of patients treated with strabismus surgery and noted the presence of compensatory head postures (CHP) in this sample.  For our purposes we need not concern ourselves with the surgical outcomes, but instead with the pre-surgical relationship between CHP and five classes of eye conditions.  Authors noted a 56.7% incidence of CHP in this five year patient sample.  Within this sample, 71.2% of superior oblique palsy cases and 100% of congenital motor nystagumus cases presented with CHP. 

Authors note that, “Because CHP is seen frequently in strabismus and nystagmus disorders, ocular causes must be ruled out in any case of an anomalous head posture.”  Note that tens of millions are estimated to suffer undiagnosed eye conditions (Maino 2010).  However, ocular causes need not rise to serious medical conditions to be considered in movement analysis.  Sometimes deviations may be too insignificant to worry about, but other times it demands specialized treatment short of surgery.  Simple awareness and a willingness to think interdisciplinarily is a good starting point.     

Head tilt is not merely linked to left-right imbalances.  Instead, a head tilt may also affect stereoacuity, which is one measure of depth perception.  Lam (2008) noted that “Head tilt to either the left or right creates a relative decrease in interpupillary distance (IPD) with regards to the horizontal plane. This effective decrease in IPD results in a decrease in a subject's stereoacuity. Additionally, the greater the head tilt, the greater the loss of stereoacuity. This information is useful in counseling individuals, especially those engaged in activities where stereoacuity is critical to performance, to make a special effort to maintain a straight head position.”

Another example comes from a study on temporomandibular joint dysfunction, or jaw pain (TMJ).  Pradham (2001) found in a study of 25 TMJ patients and 25 controls, “that eye dominance and direction of head rotation are strongly associated in both TMJ and control subjects. Further, in TMJ subjects, mandibular deviation occurred in greater frequency than in controls and tends to occur in the contra lateral direction of head rotation.”  In other words, eye dominance may lead to head rotation with our without pain.  However, in TMJ patients, the jaw typically rotated in the opposite direction of the head.  The underlying cause is unclear: is this driven by the jaw, the eyes, or the head…or a combination of all three?  Despite the unanswered questions, the correlation is robust and shows the importance of considering the eyes in all interventions.   

Fortunately, coordination between vision and movement is trainable.  Training can either hold the eye position constant and make requisite adjustments to the head/body, or can hold body position constant and retrain the eyes.  (“Binocular visual feedback is used to continually calibrate binocular eye alignment so that the retinal images of the two eyes remain in correspondence…vertical eye alignment can be altered by training to disparities that vary as a function of orbital eye position. The present experiments demonstrate that vertical eye alignment can also be trained to differ with head position when eye position (with respect to the orbit) is held constant” Maxwell (1996))

Conclusion

When eye professionals make changes to the eyes, it’s not automatic that the body will reset.  Likewise, when we make changes to the body, it’s also not automatic the eyes will reset.   Sometimes changes will occur automatically, but not always.  A multidisciplinary approach is critical.  Occasionally we’ll see eye therapy paired with occupational therapy to change workplace ergonomics as one example, but rarely does this transfer to athletics (and it also seems rare in clinical practice, due in part to professional turf wars and insurance limitations, but we ain’t goin there!). 

The interdisciplinary scope expands further when we consider the impact of vision on learning.  The kid diagnosed as ADD who is picked last for every team?  There’s a good chance he/she has unchecked vision issues leading to limited concentration, poor coordination, and lowered self-image due to impaired achievement.  The eyes take us deep places into the brain.  Vision demands utmost respect by movement specialists.

References

Kraft SP, O'Donoghue EP, Roarty JD.  Improvement of compensatory head postures after strabismus surgery.  Ophthalmology. 1992 Aug;99(8):1301-8.

Maxwell JS, Schor CM.  Adaptation of vertical eye alignment in relation to head tilt.  Vision Res. 1996 Apr;36(8):1195-205.

Pradham NS, White GE, Mehta N, Forgione A.  Mandibular deviations in TMD and non-TMD groups related to eye dominance and head posture.  J Clin Pediatr Dent. 2001 Winter;25(2):147-55.

Tedorescu, L.  Anomalous Head Postures in Strabismus and Nystagmus - Diagnostic and Management.  April 2010.  Vol. 4 No.1

Maino D. The binocular vision dysfunction pandemic. Optom Vis Dev.  2010;41(1):6-13.

Lam DY, Cheng TL, Kirschen DG, Laby DM.  Effects of head tilt on stereopsis. Binocul Vis Strabismus Q. 2008;23(2):95-104.

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