Post- Brain Injury Vision Therapy
Following acquired brain injury or in cases of post-concussion syndrome, it is common for many patients to present with certain visual symptoms. These symptoms include, but are not limited to: dizziness, nausea, headaches, double vision, light sensitivity and difficulty sustaining attention in busy visual scenes. While a concussion or head injury is typically multifactorial and complex, these symptoms can frequently be matched with objectively determined visual deficits in need of remediation. As a group, these deficits are commonly referred to as Post Trauma Vision Syndrome. Following injury, it isn’t uncommon for our visual system to direct itself towards the path of least resistance – meaning that there will be an embedded avoidance of tasks and specific eye movements that either elevate symptoms or negatively impact other sensory systems within our body. It is therefore, always our goal in therapy and through the prescribing of therapeutic glasses to provide guidance that will allow the visual system to avoid or limit the negative adaptations that so commonly occur.
Visual Midline Shift
One of the adaptations that we will commonly observe following acquired brain injury is termed a visual midline shift (VMLS). When one presents with VMLS they typically will display a true misrepresentation of where they are perceiving objects in space – likely seeing them as being shifted up, down, left or right from their true location. This can be very disorienting, as one is typically not aware that they are viewing the world in this way. Commonly, this will be found when the presenting injury affects the head asymmetrically, and can understandably lead to disorientation, nausea and even a drift while walking to either the left or the right. Because a visual midline shift is an acquired imbalance, it can fortunately however be treated. As Optometrists, we are able to apply strategic sectoral patches or occlusive devices – along with use of prism (see prism blog), in order to shift one’s perception of space – and guide recovery. Considering that the majority of our motor movements are initiated by the information supplied by our eyes, altering a visual midline shift can drastically improve the symptoms and struggles of many recovering patients.
Struggles with eye-teaming (binocularity) and accommodation (focusing) are another extremely common area of deficit uncovered following head injury. The neurological drive for these particular skills does not originate from within the eyes themselves, and so both can be heavily impacted by injuries that occur away from the front of the head. Symptoms of blur, headaches, aversion to reading or computer work and double vision will commonly be cited by individuals with these disorders. Strategic prescribing of glasses can once again provide immediate and measurable improvements in this group. In-office rehabilitation does however tend to be the most effective means by which to enact long-term change and improve symptoms.
Peripheral Vision and Head Injuries
We often think of our peripheral vision (side-vision) as being an embedded and static system that simply “sees” all of the world around us. Following head injury, along with in cases of classroom or reading difficulty, our peripheral visual awareness (or, “where is it” pathway) and integration of this system with our central “what is it” pathway tends to be impaired. This does not necessarily mean that one cannot “see” objects around them, but that they are overwhelmed by the motion and excess stimulation that they are exposed to. Essentially, one has a hard time integrating all of the excess peripheral information with what they are truly intending to see (termed “figure-ground” differentiation). Once again, therapeutic prescribing of glasses, prism and even specific tints and frequencies used permanently or in short bouts (known as syntonic phototherapy) can have an extremely positive impact on one’s peripheral visual awareness, spatial orientation and overall visual comfort while reading or in busy visual scenes.
As can be expected, Post Trauma Vision Syndrome and its component deficits do not tend to operate in isolation. Vestibular (inner-ear), musculoskeletal and a multitude of other challenges and deficits are commonly present in unison. As such, collaborative care and management by a number of professionals is always in the best interest of those presenting with these struggles. As a sensory system, however, vision is meant to lead – and so the issues and deficits mentioned in this article must be assessed and treated in order to ensure maximal recovery with minimal negative adaptations.
Until next month,
Contact Okanagan Vision Therapy in Kelowna for in-office rehabilitation