Home-based Treatment of Binocular Eye Dysfunction in Veterans with Traumatic Brain Injury

About This Grant

Background: Traumatic Brain Injury (TBI) is a common problem that affects both military and civilian populations. Although most individuals with TBI recover from the acute cognitive effects of the injury, sensorimotor symptoms often persist. One frequently occurring post-concussive symptom is impairment of near vision. This may manifest as overt diplopia or as new difficulties reading and maintaining focus on near objects. Such symptoms have been attributed to TBI-related convergence insufficiency, but this relationship remains controversial given limited data and the lack of robust and reliable tools to measure vergence function in routine clinical settings. Even when accurately diagnosed, treatment options for convergence insufficiency are limited and generally require direct supervision of a trained optometrist or vision therapist. Moreover, home vision therapy is particularly challenging, because exercises cannot be precisely matched to a particular patient’s vergence deficit, there are few objective measures of functional improvement to judge progress and titrate therapy, and it is difficult to monitor whether a patient is following the therapy plan and performing the exercises correctly. Objective / Hypothesis: This project is based on the overall hypotheses that veterans with TBI and binocular vision symptoms have disturbances of vergence control that can be treated with custom virtual-reality games and that it is feasible to provide this vision therapy in veterans’ homes. Our preliminary data show that many Veterans who have experienced TBI and who report ongoing problems with near vision have impaired static (as measured by a virtual NPC) and dynamic (as measured by responses to abrupt changes in the virtual distance of a fixation target) convergence. The proposed project includes a pilot home VR-based vision therapy trial to test the feasibility of this approach to rehabilitation and to acquire preliminary data for Hypothesis 2 that will support design and powering of a future clinical trial. Specific Aims 1) To investigate the relationship of convergence insufficiency to reading and functional near vision symptoms after TBI. 2) To test the feasibility of custom VR games for home vision therapy of binocular vision and reading impairment after TBI. 3) To assess the effect of custom vision therapy games on binocular vision and reading after TBI Study Design: The first aim will employ a virtual-reality headset with integrated high-speed eye tracking to test static and dynamic vergence and visual function in a group of adults with recent and chronic TBI with and without convergence insufficiency (defined by the near point of convergence, measured in VR). Additional tests will assess cognitive processing related to reading (WIAT reading subscales) and accommodation (for younger participants). Participants with convergence insufficiency will undergo a pilot trial of custom VR games for home vision therapy with a six-week exercise protocol using a crossover design. Aim 2 will examine the feasibility of this home therapy and Aim 3 will provide preliminary efficacy data to support future clinical trial design. Impact: This study will provide critical new information regarding the underpinnings of near vision and reading impairments after TBI, and it will lay the foundation for more precise and accessible home-based vision therapy. If successful, it will provide a novel tool for ameliorating a common and functionally disabling post-concussive symptom that affects many veterans.