The American Medical Society for Sports Medicine position statement: concussion in sport states that, “While the majority of concussions resolve within 7–10 days, in some cases symptoms persist for weeks, months or years beyond the initial injury.”
Those who suffer from chronic concussion-based symptoms, at the root of these symptoms are typically visual problems, that left untreated can be tough to deal with. From the words of one of our patients, “My journey started about 5 years ago when I had a pretty significantly hit to my head. Shortly after that, I began to notice some negative changes in my vision. My eyes would become fatigued after the simplest of visual tasks. They felt like they were being pulled apart when reading anything up close, I had blurry vision, double vision, light sensitivity, and headaches. It got to the point where I would completely avoid using a computer, TV, etc. Even driving made my eyes symptomatic. It was a tough time for me to say the least.”
Indeed, persistent visual problems and related frustration are often found in these individuals with chronic concussion-based symptoms. Therefore, the first step should begin with a referral to a vision care provider for a comprehensive eye health and vision evaluation including a refraction for glasses. Yet, while this might seem like the solution to the problem; if the doctor limits the evaluation to eye health and refraction for glasses alone, key categories of visual function related to eye coordination involving binocular vision/vergence (eye teaming), accommodation (eye focusing) and oculomotor function (eye tracking) can be overlooked.
An important example of eye coordination involving binocular vision involves testing of the two eyes performing “convergence”. If the doctor does a procedure called the Near Point of Convergence Test, they will often find the patient with post-concussion symptoms to exhibit difficulty with convergence to a normal ability (<7cm). As a result this would typically be diagnosed as Convergence Insufficiency.
But wait…just published, new research by Harvard Medical School, Department of Ophthalmology in the American Journal of Ophthalmology entitled: Post-Concussion: Receded Near Point of Convergence is Not Diagnostic of Convergence Insufficiency.
Receded Near Point of Convergence NOT diagnostic of convergence insufficiency? Isn’t this a contradiction? When I first read the headline my first thought was, surely this can’t be true. In all my years and clinical experience evaluating those with chronic concussion-based symptoms, a reduced Near Point of Convergence (NPC) and Convergence Insufficiency diagnosis is very common.
However, maybe the authors selected the title for this article as a clever strategy to grab our attention and suggest that we not get so fast with a quick diagnosis based on a single test. Because when you read the conclusions of the research it is in fact very consistent with clinical experience. Yes, these patients do have a reduced NPC, but it is much more serious than that. And, quite frankly, that’s the key to understanding these patients with chronic concussion-based symptoms.
Here is what they found:
In their research, patients who had chronic concussion-based symptoms, 89% had a receded Near Point of Convergence! However, what they also found was, the majority of these post concussion patients had an array of oculomotor, accommodative and binocular/vergence dysfunction. Put another way, their reduced NPC was just the “tip of the iceberg”.
In addition the researcher’s found of the 89% of those patients with a receded NPC:
- 95% had an oculomotor disorder
- 84% had deficits in accommodation (solely 41% or in combination with vergence disorders 43%)
- 54% had vergence disorders (also usually accompanied by an accommodative disorder 78%)
- Where as, convergence insufficiency “standing alone”, was found in only 6% of the cases
Therefore, their final conclusion reads: “Because treatment options for the various oculomotor dysfunctions differ, it is prudent that these patients (with concussion-based symptoms) undergo a thorough examination of their vergence and accommodative systems so that an accurate diagnosis can be made and appropriate treatment prescribed.”
As outlined by the American Optometric Association in the Clinical Practice Guideline (CPG-18) for Accommodative and Vergence Dysfunction, the treatment of choice is office-based optometric vision therapy/rehabilitation for those with binocular/vergence, accommodative and oculomotor dysfunction.
For those patients who are experiencing chronic concussion-based symptoms, appropriate and effective treatment for these complex sensorimotor problems, is not a series of take home eye exercises or just a variety of saccadic eye movement routines. It requires a sophisticated office-based approach to integrate binocular/vergence function with accommodation and oculomotor function by a skilled vision therapist applying appropriate lenses, prisms and/or therapeutic tints prescribed and supervised by an experienced Doctor of Optometry who specializes in developmental vision and rehabilitation.
Dan L Fortenbacher, O.D., FCOVD