Training Oculo-motor Control to Improve Vision When Using a Preferred Retinal Locus

Study Overview
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Brief Summary
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When high-detail vision is lost due to a retinal disease such as macular degeneration, people see poorly, and have difficulty with eye movements (oculo-motor control). This preliminary study will investigate a potential behavioral intervention that may improve the ability to perform vision-related daily activities such as reading, recognising faces and watching television. The intervention involves many sessions that will train visual perception and eye movements over a period of a few months. Participants will have either lost central vision in both eyes or have normal vision (control group).

Detailed Description
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The purpose of the study is evaluate a potential treatment for loss of (foveal) central vision in both eyes which results in the use of a preferred retinal locus (PRL). The treatment is a series of 16 sessions of about one-hour duration that will involve a mixture of oculomotor control (OMC) training, perceptual training, and scotoma awareness. Two groups will receive the training: (1) central vision loss; and (2) normal sight who will use a simulated scotoma (called control group below). A single-site, two-way mixed factor, one within-subject and one between-subject, minimal-risk phase-2 study. Each participant with vision loss or in the control group will attend for three outcome-measurement visits and 16 training visits over a period of about two months (at 2 visits per week). Feasibility metrics will be obtained during recruitment and study conduct. PRL and OMC metrics will be obtained at every visit. Outcome metrics will be obtained before treatment, following 8 training sessions, and following 16 training sessions. Participants in the control group will experience a simulated central scotoma created by a gaze-contingent visual display system that simulates the loss of central vision by obscuring a region of central vision during testing and training. Participants will be trained using an integrated oculo-motor and perceptual training approach using a gaze-contingent visual display to provide scotoma awareness. Two tasks will alternate: (1) a textured search target that suddenly shifts, drifts smoothly, or is stable, requiring the subject to make a saccade, a smooth pursuit, or fixate, respectively, following which there is a same-different task to test attention; and (2) target following and visual search for (a) face within distractors, (b) object recognition and location, and (c) word recognition and object identification over cluttered background. During training, for the vision-loss group, the binocular scotoma (created by the retinal lesions) will be outlined using a gaze-contingent system, so that the subject will see a border at the edge of their binocular scotoma that moves with gaze, alerting them to the location of the scotoma. In addition to the 16 training sessions, there will be longer (2.5 to 3 hours) measurement sessions: (1) before training; (2) after 8 training sessions; and (3) after 16 training sessions. Due to the number of procedures, the first measurement session might consist of two sessions. Thus, each participant with vision loss will participate in 19 or 20 sessions in total. Ideally, participants will attend for two visits per week. However, the schedule is flexible and can be adapted to a participants schedule.

Official Title
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Training Oculo-motor Control to Improve Vision When Using a Preferred Retinal Locus

Conditions
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Central Visual Impairment

Intervention / Treatment
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* Behavioral: Training of perception and oculo-motor control


Participation Criteria
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Eligibility Criteria
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Central Vision Loss Group Inclusion Criteria: Bilateral foveal loss that includes the fovea in each eye, as determined through retinal examination fluent in English Cognitive function MoCA (Montreal Cognitive Assessment) test >20 Binocular visual acuity 20/800 or better able to sit for at least an hour Exclusion Criteria: speech impediment history of neurological or psychiatric disease inability to provide informed consent inability to follow instructions in English Normal Vision Control Group Inclusion Criteria: fluent in English Cognitive function MoCA (Montreal Cognitive Assessment) test >25 Binocular visual acuity 20/40 or better able to sit for at least an hour Exclusion Criteria: any ophthalmic disease that might impact on the conduct of the study, especially conditions that cause vision field loss speech impediment history of neurological or psychiatric disease inability to provide informed consent inability to follow instructions in English

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Non-Randomized
Intervention Model: Parallel Assignment
Interventional Model Description: Two-way mixed (one within, one between) factor study. Same training, applied to central vision loss group and normal vision control group viewing with simulated central scotomas.
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: central vision loss<br>will receive behavioral intervention | Behavioral: Training of perception and oculo-motor control<br>* Behavioral training of eye movements and perception<br>|
| Active Comparator: normal vision<br>using simulated central scotomas, will receive behavioral intervention | Behavioral: Training of perception and oculo-motor control<br>* Behavioral training of eye movements and perception<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| reading speed following eight training sessions | reading of paragraphs of text | comparing reading speed before intervention and after 8 sessions of training | 
| reading speed following sixteen training sessions | reading of paragraphs of text | comparing reading speed before intervention and after 16 sessions of training | 
| face discrimination threshold following eight training sessions | recognizing differences between faces | comparing face discrimination thresholds before intervention and after 8 sessions of training | 
| face discrimination threshold following sixteen training sessions | recognizing differences between faces | comparing face discrimination thresholds before intervention and after 16 sessions of training | 
| video comprehension (shared word score) following eight training sessions | understanding and describing the content of short video clips | comparing shared word scores before intervention and after 8 sessions of training | 
| video comprehension (shared word score) following sixteen training sessions | understanding and describing the content of short video clips | comparing shared word scores before intervention and after 16 sessions of training | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| PRL location relative to the location before the intervention (training) | location of the preferred retinal locus measured from a retinal image obtained during a fixation examination | location at each of the 16 training sessions as compared to the location before intervention | 
| Oculo-motor reference location relative to the location before the intervention (training) | first landing location of saccades to a new location measured using a gaze tracking system; measures whether there has been an adjustment of eye movement planning | at each of the 16 training sessions as compared to the location before intervention | 
| saccade dynamics relative to the location before the intervention (training) | slope of the saccadic main sequence, which is the speed to distance relationship of saccades (fast eye movements), as measured using a gaze tracking system | at each of the 16 training sessions as compared to the location before intervention | 
| single-letter visual acuity following eight training sessions | ability to read single letters of varying size | comparing visual acuity before intervention and after 8 sessions of training | 
| single-letter visual acuity following sixteen training sessions | ability to read single letters of varying size | comparing visual acuity before intervention and after 16 sessions of training | 
| letter contrast sensitivity following eight training sessions | ability to read large letters of low contrast | comparing letter contrast sensitivity before intervention and after 8 sessions of training | 
| letter contrast sensitivity following sixteen training sessions | ability to read large letters of low contrast | comparing letter contrast sensitivity before intervention and after 16 sessions of training | 
| Geriatric Depression Scale (GDS) following eight training sessions | evaluate depression and aspects of quality of life | comparing GDS scores before intervention and after 8 sessions of training | 
| Geriatric Depression Scale (GDS) following sixteen training sessions | evaluate depression and aspects of quality of life | comparing GDS scores before intervention and after 16 sessions of training | 
| Veterans Affairs Low Vision Visual Functioning Questionnaire (VA LV VFQ) following eight training sessions | measure of visual ability and vision-related limitations | comparing VA LV VFQ scores before intervention and after 8 sessions of training | 
| Veterans Affairs Low Vision Visual Functioning Questionnaire (VA LV VFQ) following sixteen training sessions | measure of visual ability and vision-related limitations | comparing VA LV VFQ scores before intervention and after 16 sessions of training |