Vision and Concussions

The visual system is often significantly affected by concussive injury. In some, symptoms of visual dysfunction may resolve in a short time frame, while in others symptoms may be ongoing for weeks or even months. Symptoms of visual dysfunction following head trauma may include headache, eye pain, difficulty reading, dizziness, focusing issues, and double vision.

For athletes suffering from persistent concussion-related symptoms, it is vital that they undergo visual screening to determine if a dysfunction is present. Most disorders of the visual system following head trauma are highly treatable if identified.

At Shift, our Health Professionals are trained to identify those athletes who may be suffering from a visual dysfunction post-concussion, and to refer them to a qualified Optometrist for assessment and rehabilitation as required.

Why Eyecare matters

A message from IRIS


How Does Concussion Affect Vision?

Traumatic Brain Injury (TBI), which in fact concussions are, can have major effects on the visual system despite neuro-imaging showing normal results. In essence, concussions and TBIs usually cause a form of “bruising of the brain” (i.e. a contra-coup injury) whereby function is often affected but yet no structural damage is apparent. The constellation of eye co-ordination issues and dizziness post concussion have been termed “Post-Trauma Vision Syndrome” or PTVS and has actually been described in the literature already. The main symptoms of PTVS are dizziness, gait issues, focussing issues, headaches and double vision. At our Guelph clinic, we are in fact specifically noting that patients that have more severe PTVS tend to have a history of prior eye co-ordination issues. The problem is that these symptoms are quite different and in fact are usually causative of reading and tracking problems in the academic realm.

I started my research career in glaucoma, which is actually a degenerative optic nerve disease (i.e. glaucoma, even though it is an eye condition, is in fact a neuro-degenerative condition). Whilst writing my PhD thesis I realized how complex the visual system was and started to look closer at some of my pediatric patients with eye co-ordination issues and realized very quickly that in most cases, there were significant anomalies of eye co-ordination present. In 2013, we have just published a paper linking over 13 measured of eye co-ordination specifically to reading ability (and the reading skill was assessed with an infra-red tracking system so you can actually see the child reading in real time!). Hard to argue with the results and conclusions, thus a top rated ophthalmology journal (Graefe’s Archives of Clinical & Experimental Ophthalmology) published it without hesitation. Over time, we started to notice that many of the teen and adult concussion patients we saw in practice tended to have similar eye teaming issues to the developmental cases we treated, but with one exception. The eye co-ordination was markedly more impaired in the concussion patients BUT…the more severe cases tended to have a prior history of eye tracking issues as reported by greater difficulty at school. This is currently the main focus of our research at present. It is my strong belief that all children or adults engaged in sports with a high risk of concussion should have baseline testing done to establish wither their binocular vision status is intact or “borderline” and any athletes with borderline function should have this addressed. This makes ample sense, as the patients with poorer binocular vision will tend to have a greater impact on their system with concussions (that also cause binocular vision issues). In essence, the concussion can simply be the “straw that breaks the camel’s back”.

As there is ample literature to date showing that optometric vision therapy can be highly effective for the remediation of non-strabismic binocular vision disorders (i.e. the Convergence Insufficiency Treatment Trial or CITT Study) it makes ample sense that this baseline testing be considered in all athletes with high risk of concussion injuries. For more information on vision therapy, see

Dr. Patrick Quaid, MCOptom(UK), FCOVD(USA), PhD(CAN) of IRIS