Wednesday, June 4, 2014

Eye movement dysfunctions, their treatment and reading related problems in patients with mild traumatic brain injury (mTBI)

We have large vision therapy practice at our Vancouver vision and eye clinic where one category of patients that we treat come to us with traumatic brain injuries that have caused vision problems in the patients, including reading difficulties.  

Reading is a complex task involving a number of functions, abilities and visual skills.  Reading has oculomotor, sensory, cognitive, and attentional components, and all of these must be integrated. If any one of them is affected by a brain injury, they reading is likely to be negatively affected as well.   For example, accurate eye movements are essential for efficient reading. This means that if a traumatic brain injury (TBI) has affected the normal control of eye movements, then reading will likely be adversely impacted.

How can doctors fix these problems?  That was the issue investigated by the authors of a study published in 2007 in the Journal of Behavioral Optometry.  The researchers looked at three studies done by their research group which involved versional oculomotor dysfunctions, their related reading problems, and treatment in a group of patients with mild TBI whose injury affected their vision and reading ability.

Let's take a second to make sure we understand a few of those scientific terms.  A "version" is an eye movement involving both eyes moving together as a team in the same direction.  A "versional oculomotor dysfunction" is a problem in the way the eyes move together as a team.

The results have shown that in a large clinical sample (160 patients), approximately 90% had one or more oculomotor deficits, such as convergence insufficiency or abnormal saccadic tracking- a saccade is a fast movement of the eye like the moments the eye does when tracking words on a printed page.  Deficits in these areas have the potential to interfere with reading performance.  

Out of the 160 patients examined, thirty-three of them completed a program of vision therapy. Of the patients who received vision therapy, an impressive ninety percent of them experienced improvement in at least one related sign and one related symptom. 

The researchers also laboratory-tested 9 of the study subjects who had  eye-movement-related reading problems and found that all of them improved their overall reading performance and versional eye tracking ability after vision therapy.

There are a number of conclusions to draw from this study:
  1. eye movement dysfunctions are common in individuals with mild TBI;
  2. vision therapy can effectively treat eye movement dysfunctions;
  3. the positive vision therapy findings demonstrate that the adult brain can be changed and molded (re-wired) with vision therapy and this shows the presence of considerable neuroplasticity in adults with mild traumatic brain injury;
  4. optometric vision therapy should be used to treat  visually symptomatic patients with TBI who have eye-movement-based reading problems.

More information

To learn more about vision therapy and brain injuries, visit:
Another excellent resource is the website of NORA, the Neuro-Optometric Rehabilitation Association.


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Eye movement dysfunctions, their treatment and reading relateed problems in patients with traumatic brain injury
Dec 28, 2012

Vision problems after car accident are caused by brain injury 
Nov 07, 2012

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Image courtesy of Victor Habbick /