ARBi - Assessment and Rehabilitation of Binocular Sensorimotor Disorders

PROJECT SUMMARY
Binocular vision relies on a synergy between sensory and motor fusional mechanisms that jointly construct a
single percept of the environment from the differing images formed on the two retinae. A stereoscopic sensory
representation of the environment is required for accurate binocular eye movements, which in turn are required
for stereoscopic sensory vision. A failure in either component of this system, especially during development, can
lead to permanent binocular vision impairment. Sensory impairments can include amblyopia, diplopia and
suppression, oculomotor impairments can include strabismus and vergence insufficiency, while socio-economic
sequelae include lost education, sport and job opportunities and elevated adverse health risks. The current
treatments for amblyopia (occlusion and penalization) are primarily monocular and do not promote binocular
perception or eye movement coordination. Similarly, treatments for strabismus do not typically address binocular
perception. These limitations are at least partly due to a lack of practical methodologies for the assessment of
sensory-motor function and partly due to a lack of coordinated sensory-motor therapies.
Recent data show that there is significant plasticity in both sensory systems and motor systems, even in adults.
Many groups are now exploring methods to promote sensory plasticity with digitally modified images in
dichoptic games and movies, but considerably less attention has been directed to motor plasticity or sensory
and motor plasticity together. We hypothesize that additional therapeutic gains and a lower risk of adverse side
effects may be achieved with a combined sensory-motor therapeutic approach that is monitored by effective
sensory-motor endpoints. We argue i) that the pace of commercialization of virtual reality therapies for
anisometropic amblyopia intensifies the need simultaneously to understand sensory and oculomotor deficits in
strabismic amblyopia and ii) that the high levels of recidivism following surgical intervention may benefit from
combined sensorimotor rehabilitation. In Aim 1, we develop and evaluate efficient methods to measure sensory
and motor deficits in people with binocular vision impairment and to provide a quantitative framework for
evidence-based assessment of sensory-motor therapy. In Aim 2, we measure the impact across the visual field
of strabismus on the three-dimensional representation of virtual and natural environments to understand how
the distribution of naturally occurring depth statistics across the visual field may impact the development of
binocular sensory and motor deficits and moderate their response to treatment. In Aim 3, we develop and
evaluate feedback-based methods that aim to facilitate and maintain ocular alignment and examine the
potential benefit of simultaneous sensory and motor interventions for binocular visual function. In each Aim, we
employ both laboratory stimuli, because of their high level of control, and natural and virtual 3D scenes,
because of their rich structure and relevance to real-world deficits. The overall goal is to demonstrate the
theoretical foundation for combined sensory and motor therapeutic approaches to binocular visual dysfunction.

Grant Number: 5R01EY032162-05
NIH Institute/Center: NIH
Principal Investigator: Peter Bex