Obstacle Negotiation in Older People With and Without Vision Impairment
Study Details
Study Description
Brief Summary
Falls are common among people with vision impairment and can lead to devastating health consequences. Understanding the functions of vision and how the visual characteristics of obstacles in the walking path impact the gait of people with vision impairment is necessary to create strategies to prevent falls in this population. The purpose of this study is to determine how adults with vision impairment change their gait behavior when stepping over obstacles that vary in height and contrast to the ground. We will then determine the mechanisms of gaze behavior that correlate to the gait behavior.
| Condition or Disease | Intervention/Treatment | Phase |
|---|---|---|
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N/A |
Study Design
Arms and Interventions
| Arm | Intervention/Treatment |
|---|---|
| Experimental: Low Vision Group At a single study visit, the group of low vision participants will be asked to perform a series of short walking trials. During each trial they will walk at a self-selected speed along a walkway (18 meters in length) that may or may not contain an obstacle to step over. The trials will be randomly varied with regard to an obstacle's presence, height, and contrast from the walkway surface. Repeated trials of each condition variation will be performed during the visit. |
Other: Obstacle characteristics
In the walking trials, when an obstacle is present, the obstacle height and obstacle contrast level will be varied across the trial repetitions.
Each participant will be exposed to obstacles of two heights: the first will be 1 centimeter in height, and the second will be approximately 20% of the subject's leg length (ranging in physical height between 16 - 22 centimeters to cover a range of leg lengths in the population).
Obstacles (of both heights) will also be painted such that their measured luminance (or contrast) level against the floor luminance is varied. High contrast obstacles will have approximately 90% Michelson contrast and low contrast obstacles will have approximately 6% Michelson contrast.
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| Active Comparator: Control Group At a single study visit, the group of age-matched participants without low vision will be asked to perform a series of short walking trials. During each trial they will walk at a self-selected speed along a walkway (18 meters in length) that may or may not contain an obstacle to step over. The trials will be randomly varied with regard to an obstacle's presence, height, and contrast from the walkway surface. Repeated trials of each condition variation will be performed during the visit. |
Other: Obstacle characteristics
In the walking trials, when an obstacle is present, the obstacle height and obstacle contrast level will be varied across the trial repetitions.
Each participant will be exposed to obstacles of two heights: the first will be 1 centimeter in height, and the second will be approximately 20% of the subject's leg length (ranging in physical height between 16 - 22 centimeters to cover a range of leg lengths in the population).
Obstacles (of both heights) will also be painted such that their measured luminance (or contrast) level against the floor luminance is varied. High contrast obstacles will have approximately 90% Michelson contrast and low contrast obstacles will have approximately 6% Michelson contrast.
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Outcome Measures
Primary Outcome Measures
- Vertical foot clearance, lead limb [During a single intervention visit (Study Visit 2), up to 2-3 hours in duration.]
Distance from lowest point of foot (heel or toe) to top of obstacle
- Foot placement variability [During a single intervention visit (Study Visit 2), up to 2-3 hours in duration.]
Standard deviation of position of toe to obstacle over 2-4 steps before the obstacle
- Obstacle crossing speed [During a single intervention visit (Study Visit 2), up to 2-3 hours in duration.]
Speed from lead toe off immediately before the obstacle to trail heel down immediately after the obstacle.
- Gaze sequencing [During a single intervention visit (Study Visit 2), up to 2-3 hours in duration.]
Sequence of fixations from start of trial to end of trial, normalized to the total duration and divided into 100 equal segments
Eligibility Criteria
Criteria
Inclusion Criteria:
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Age 18 or over
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Able to walk independently
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Either have normal vision, or low vision, defined as either Central field loss (CFL) or Peripheral Field Loss (PFL).
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CFL will be defined as a condition that affects macular function resulting in a binocular visual acuity of 20/30 or worse, with or without a central scotoma.
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PFL is defined as a binocular visual field that is restricted to an average of 100 degrees in diameter or less.
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Control participants will have visual acuity of 20/60 or better and will not have a history of any conditions that can cause central field loss or peripheral field loss
Exclusion Criteria:
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Not cleared by a medical provider for moderate physical activity
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Self-report or have a history of: vestibular disorder or deafness
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Medical history of any condition that affects the ability to walk for up to 2 hours with breaks, such as feeling dizzy or faint, chest pain, palpitations, pain or numbness in the legs, shortness of breath,
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Cognitive limitations either by self-report or a score on the Mini Mental State Exam below 24 (out of 30)
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Walking or gait abnormalities, such as those caused from an injury, surgery, severe arthritis, or neurological condition such as Parkinson's disease
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Unable to walk without any walking aids such as a walker, cane, guide dog, or oxygen tank.
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Does not speak English
Contacts and Locations
Locations
| Site | City | State | Country | Postal Code | |
|---|---|---|---|---|---|
| 1 | Indiana University | Bloomington | Indiana | United States | 47405 |
Sponsors and Collaborators
- Indiana University
Investigators
None specified.Study Documents (Full-Text)
None provided.More Information
Publications
None provided.- 16447