Feasibility Tests for Various Prism Configurations for Visual Field Loss

Study Overview
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Brief Summary
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The investigators will develop and test different configurations of high-power prisms to expand the field of vision of patients with visual field loss to assist them with obstacle detection when walking. The study will involve multiple visits (typically four) to Schepens Eye Research Institute for fitting and testing with the prism glasses. The overall objective is to determine best designs and fitting parameters for implementation in prism devices for future clinical trials.

Official Title
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Visual Field Expansion Through Innovative Multi-Periscopic Prism Design

Conditions
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Hemianopia, Homonymous, Tunnel Vision, Visual Field Defect, Peripheral, Visual Field Constriction Bilateral, Visual Field Defect Homonymous Bilateral

Intervention / Treatment
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* Device: High power prisms


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Visual field loss, either peripheral field loss or hemianopic field loss Visual acuity of at least 20/50 in the better eye In sufficiently good health to be able to complete sessions lasting 2-4 hours Able to independently walk short distances Able to give voluntary, informed consent Able to speak English Exclusion Criteria: Any physical or mental impairments, including cognitive dysfunction, balance problems or other deficits that could impair the ability to walk or use the prism spectacles A history of seizures in the last 6 months Hemispatial neglect (subjects with hemianopic field loss only)

Ages Eligible for Study
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Minimum Age: 7 Years
Maximum Age: 80 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Device Feasibility
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: High power prisms<br>Various configurations of high power prisms will be developed for each individual and custom fit into spectacles lenses. | Device: High power prisms<br>* High power prisms designed to shift images from blind areas into portions of the wearer's remaining, seeing, field of vision<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Field of view expansion | Horizontal and vertical extent of the expansion (in degrees) of the field of view | Through study completion, an average of four months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Pedestrian detection rate | Proportion of pedestrians detected (in simulated walking or simulated driving) | Through study completion, an average of four months | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Visual field expansion, Prisms, Hemianopsia, Tunnel vision, Visual field loss