What is Post Traumatic Vision Syndrome?
Post Traumatic Vision Syndrome (PTVS) is a diagnosis often present in patients, after a head (i.e., TBI) or neurological (i.e., CVA) injury, who have an unstable, or impaired, an ambient visual process whereby their spatial vision has become disorganized. It is based on the theory that there are two separate processes in the visual system: focal and ambient. The focal represents the ability to focus in detail on an object using, for the most part, the macula. The ambient represents the ability of the peripheral vision to provide information about balance, movement, coordination, and posture necessary for spatial orientation. Relating to the vision anatomy, nerve fibers from the peripheral part of the retina that form the ambient visual process travel to the midbrain where the superior colliculus, involved in spatial orientation and eye movement control, integrates the spatial information with other sensorimotor systems and proprioceptive base of support (BOS). The ambient system depends on this integration to inform a person where he/she is in space and where he/she is looking before processing what the visual information, being seen, is. Dysfunctions at the midbrain level following any neurological event can affect the ambient visual process. Furthermore, in PTVS, the focal system operates on overdrive and is no longer harmonious with the ambient system on which it depends on.
Since the eyes are the only two organs in the brain that move and more than 80 percent of all sensory processing in the entire body is directly affected by information coming in from them; it is not uncommon that neuropathological changes will influence the visual system in some way. Numerous studies show at least 30 percent of patients with TBI suffer from visual dysfunctions, with one such study finding a 90 percent incidence of post-trauma visual complications. Those undiagnosed with, or untreated for, PTVS can have persistent, evolving, limiting issues affecting activities of daily living that can last years after the initial trauma.
Diagnosing Post Traumatic Vision Syndrome
The signs or features of PTVS are, in part, dysfunctions of the ambient visual process and have binocularity issues such as exotropia, exophoria, convergence insufficiency/infacility, and/or accommodative insufficiency/paresis/paralysis, oculomotor dysfunction, visual-spatial dysfunction, and also visual-perceptual/cognitive deficits.
Usually, symptoms differ from one individual to another and they manifest as functional interferences rather than structural abnormalities with no irregularities on standard structural neuro-imagings. They consist of any or a combination of the following: asthenopia, double vision, blurry vision, headaches, difficulty with reading such as losing one’s place or skipping/re-reading lines, difficulty with scrolling digital devices, movement of stationary objects such as prints, walls and floor, light/motion sensitivity, post-traumatic migraines, reduced depth perception, uneasiness maneuvering through space, dizziness/vertigo, balance and posture/gait issues, cervical dysfunction, discomfort in crowded/busy spaces/patterns, reduced/slow visual information processing, problems with memory recall and remembering what was seen and psychological and mood consequences including lack of confidence, anxiety and panic disorders.
To investigate the symptoms associated with PTVS, a neuro-optometric assessment in multiple disciplinary areas is necessary, in addition to the standard eye examination that evaluates visual acuity, refraction, visual field, and ocular health. This extended, specialized, neuro-vision examination provides additional information about any dysfunction, if present, in the relationships between the visual processes, the sensorimotor systems, and the proprioceptive BOS as they interact with the environment. It is a comprehensive analysis of the following: gaze steadiness, scanning, and tracking aptness focussing ability/flexibility/stamina, binocularity at distance and at near in all positions of gaze, efficiency/stamina of visual process when under visual/general stress, visual field defects and peripheral awareness/attention such as visual-spatial neglect, visual-vestibular integration, VOMS (Vestibular-Ocular Motor Screening), spatial orientation or sense of position in space (Visual Midline Shift), visual perceptual/processing skills, visual-verbal automaticity, primitive reflexes and VEP (Visually Evoked Potential).
Post Traumatic Vision Syndrome Treatment
Treatment strategies for PTVS that can help stabilize the ambient visual process and increase binocular cortical function incorporate bi-nasal sector occlusion and low power base-in prisms. Other kinds of neuro-optometric rehabilitation techniques may include the following or a combination of the following: medically necessary tinted lenses, stress-relieving low power near-point correction, and syntonic phototherapy. Hereinafter, an individualized, in-clinic, vision rehabilitation program can also be implemented to empower the person to actively develop and reinforce their visual efficiency and visual processing skills so that the dual visual processes are able to organize visual-spatial information automatically, easily, and effortlessly integrating with proprioceptive and vestibular for optimum performance.
Of course, simultaneous and appropriate multi-disciplinary care with other rehabilitation health professionals is also important for the successful management and recovery of co-morbid health conditions from the brain injury and/or insult.