Development of New Approaches to Rehabilitating Vision Loss in Veterans With Age-Related Macular Degeneration

The overall goal of the proposed exploratory project is to help develop novel approaches to rehabilitating visually impaired Veterans. While the current rehabilitative approaches can be effective, there is indisputably much room for improvement. Apropos to which, recent research has provided new insights into how the brain, healthy and diseased alike, ‘makes up’ for what is impaired in one sensory modality (e.g., vision) by recruiting compensating information from another sensory modality, e.g., active (or haptic) touch. The proposed bench- to-bedside translational project seeks to evaluate the feasibility of leveraging these crossmodal research insights to help develop the next generation of rehabilitative therapies for visually impaired Veterans. The research insight most directly relevant to the present project is this: At any given time, there will be multiple different objects around us. In recruiting haptic information to help compensate for gaps in the visual information, the brain (healthy or otherwise) must have a way of deciding which haptic object corresponds to which visual object. It turns out that the brain infers that a given visual object corresponds to a given haptic object if the two objects meet one or both of the following two ‘crossmodal recruitment criteria’ (CRC): (i) The brain receives information about the two objects from the same location in the outer world, and/or (ii) It receives the information from both sources at the same time. We hypothesize that, by appropriately manipulating the given CRC, it should be possible to ‘coax’ the brain to better recruit the haptic information to better compensate for vision loss, a proposition supported by our preliminary results. Each of the two Specific Aims of the proposed study seeks to characterize the efficacy of one of the above two CRCs. Each Aim will test the hypothesis that optimal values of the corresponding CRC can help optimize crossmodal integration for each Veteran in an evidence-based fashion customized for that Veteran. To help make the proposed study directly relevant to the healthcare of Veterans, we will carry out the study procedures in older Veterans (≥50 years) with age-related macular degeneration (AMD), one of the most common causes of vision loss in Veterans in this age group. As visual and haptic stimuli, we will use the actual objects that are currently in active use at our VA to rehabilitate Veterans with visual impairments. We will use a random controlled trials (RCT) design, whereby Veterans will be randomly assigned to a Treatment or a Control Group. Patients in either Group will continue all their regular medical treatments unrelated to the present study, but subjects in the Treatment Group will additionally receive study-related visual-haptic Rehabilitative Training. All subjects in either Group will also receive periodic, study-related Outcome Testing consisting of custom-designed object recognition tests, and functional magnetic resonance imaging (fMRI) to help characterize the underlying neural correlates of rehab-dependent changes, if any. We will systematically compare the various outcome measures (i) between the Treatment vs. Control Groups, and (ii) before vs. after the rehabilitation for either Group. As detailed in the Research Plan, we will use the standard outcome metrics for feasibility studies used by US Government agencies to assess the effectiveness or lack thereof of the proposed Rehabilitative Training approach proposed in this feasibility study. The proposed study is highly innovative, in that it represents a novel application of the neuroscientific principles of optimal visual-haptic crossmodal integration to rehabilitation medicine in general, and to the rehabilitation of visually impaired Veterans in particular. The successful completion of the proposed study is also likely to be highly impactful because it will constitute a proof of the principle that visual-haptic rehabilitative training with CRC manipulation can be an effective tool for rehabilitating Veterans with AMD, and will help lay the groundwork for future larger-scale studies to develop and standardize the next generation of rehabilitative therapies for Veterans.