Visual Rehabilitation After Occipital Stroke
- Conditions
- Vision Loss PartialQuadrantanopiaVisual Field Defect, PeripheralPeripheral Visual Field DefectHemianopsiaHemianopiaVisual Fields HemianopsiaHomonymous HemianopsiaOccipital Lobe InfarctStroke, Ischemic
- Interventions
- Device: Subacute Training in the blind fieldDevice: Subacute Training in the intact fieldDevice: Chronic Training in the blind field
- Registration Number
- NCT04798924
- Lead Sponsor
- University of Rochester
- Brief Summary
This research aims to examine changes in plastic potential of the visual system with time from stroke affecting primary visual cortex. We will measure structural and mechanistic aspects of progressive degeneration along the early visual pathways, correlating them with changes in visual performance, and in responsiveness to visual restoration training. This project will advance both scientific knowledge, as well as technical capability and clinical practices for restoring vision and quality of life for people suffering from cortical blindness.
- Detailed Description
Not available
Recruitment & Eligibility
- Status
- ACTIVE_NOT_RECRUITING
- Sex
- All
- Target Recruitment
- 60
- Residents of US and Canada
- MRI and/or CT scans showing evidence of one-sided / unilateral stroke or stroke-like damage to the primary visual cortex or its immediate afferent white matter sustained less than 6-months prior to enrollment
- Reliable visual field defects in both eyes as measured by Humphrey, Macular Integrity Assessment (MAIA), Goldmann, and/or equivalent perimetry. This deficit must be large enough to enclose a 5-deg diameter visual stimulus.
- Ability to fixate on visual targets reliably for 1000ms (as demonstrated by visual fields, and verified in study participation)
- Willing and safely able to undergo magnetic resonance imaging (MRI) scanning
- Willing, able, and competent to provide informed consent
- Fluent in written and spoken English
- Cognitively able, responsible, and willing to complete daily visual training independently at home for several months.
- Past or present ocular disease interfering with vision
- Best corrected visual acuity worse than 20/40 in either eye
- Presence of damage to the dorsal Lateral Geniculate Nucleus, as shown on MRI/CT scans
- Diffuse, whole brain degenerative processes
- Brain damage deemed by study staff to potentially interfere with training ability or outcome measures
- History of traumatic brain injury
- Documented history of drug/alcohol abuse
- Currently use of neuroactive medications which would impact training, as determined by PI
- Cognitive or seizure disorders
- One-sided attentional neglect
- Inability to perform the visual training exercises as directed
Study & Design
- Study Type
- INTERVENTIONAL
- Study Design
- PARALLEL
- Arm && Interventions
Group Intervention Description Training in the blind field Subacute Training in the blind field Training in the blind field using specialized software Training in the intact field Subacute Training in the intact field Training in the intact field using specialized software Training in the intact field Chronic Training in the blind field Training in the intact field using specialized software Training in the blind field Chronic Training in the blind field Training in the blind field using specialized software
- Primary Outcome Measures
Name Time Method Direction Discrimination Threshold baseline, 6 months, 12 months For each subject, we will measure the ability to detect differences in the motion direction of visual stimuli relative to horizontal, measured in degrees of visual angle. These assessments will be based on what can be reliably detected at a 72-75% correct level of performance.
These measures of change will be evaluated baseline to 6-months post-stroke, then 6- to 12-months post stroke, and baseline to 12-months.\*\*
\*\*NOTE: Our protocol allows for a +1 month variance for all timepoints.
- Secondary Outcome Measures
Name Time Method Direction Integration Threshold baseline, 6 months, 12 months This will measure the ability of subjects to integrate across a range of motion directions measured in degrees of visual angle. These assessments will be based on what range of motion directions can be reliably integrated at a 72-75% correct level of performance.
These measures of change will be evaluated baseline to 6-months post-stroke, then 6- to 12-months post stroke, and baseline to 12-months.
\*\*NOTE: Our protocol allows for a +1 month variance for all timepoints.Ganglion cell complex volume laterality baseline, 6 months, 12 months Change in volume of the ganglion cell complex will be measured by retinal optical coherence tomography (OCT) scans from baseline to 6- and 12- months post stroke.\*\*
We will perform OCT imaging of the foveal region of the retina (6mm ETDRS) in both eyes of each patient. Images will be automatically segmented. Estimated volume of the ganglion cell complex will be extracted and aligned with estimates of the blind field's visual sensitivity obtained from fundus-controlled MAIA perimetry. We will then compute a laterality index as follows: LIGCCT=(Tc-Ti)/(Tc+Ti) where Tc=thickness in the control lateral OCT quadrant, Ti=thickness in the impaired lateral OCT quadrant.
\*\*NOTE: Our protocol allows for a +1 month variance for all timepoints.contrast sensitivity for static orientation baseline, 6 months, 12 months Assessment of visual perception transfer to untrained psychophysical tasks of contrast sensitivity for static orientation discrimination.
For each subject, we will measure the ability to correctly detect the orientation of non-moving visual stimuli that vary in contrast against a grey background. We will measure the luminance that can be reliably detected at a 72-75% correct level of performance.
These measures of change will be evaluated baseline to 6-months post-stroke, then 6- to 12-months post stroke, and baseline to 12-months.
\*\*NOTE: Our protocol allows for a +1 month variance for all timepoints.Optic Tract (OT) laterality baseline, 6 months, 12 months OT volume analysis will be performed from high resolution structural T1 MRI images of the brain. Mirrored masks of equal size will be hand-drawn over the OTs in each brain slice of a given subject, starting three slices posterior to the optic chiasm and continuing posteriorly until the OTs are no longer distinct from surrounding structures. The volume of each optic tract will be calculated from these masks by first establishing the maximum voxel intensity (range from 0 to 255) across the two OTs, then counting the number of voxels in each OT mask with brightness values between 5 and 85% of this maximum. We will then compute an OT laterality Index (LI85) to represent the relative difference in estimated volume between the two OTs of each participant, where LI85=(OTc-OTi)/(OTc+OTi), where OTc=number of voxels with brightness 5-85% of maximum in the contralesional OT and OTi = number of voxels with brightness 5-85% of maximum in the ipsilesional OT.
Ganglion cell complex thickness laterality baseline, 6 months, 12 months Change in thickness of the ganglion cell complex will be measured by retinal optical coherence tomography (OCT) scans from baseline to 6- and 12- months post stroke.\*\*
We will perform OCT imaging of the foveal region of the retina (6mm ETDRS) in both eyes of each patient. Images will be automatically segmented. Estimated thickness of the ganglion cell complex will be extracted and aligned with estimates of the blind field's visual sensitivity obtained from fundus-controlled MAIA perimetry. We will then compute a laterality index LI as follows: LIGCCT=(Tc-Ti)/(Tc+Ti) where Tc=thickness in the control lateral OCT quadrant, Ti=thickness in the impaired lateral OCT quadrant.
\*\*NOTE: Our protocol allows for a +1 month variance for all timepoints.Contrast Sensitivity for Direction baseline, 6 months, 12 months Assessment of visual perception transfer to untrained psychophysical tasks of contrast sensitivity for direction discrimination.
For each subject, we will measure the ability to correctly detect the motion direction of visual stimuli that are also varying in contrast against a grey background. We will measure the luminance contrast that can be reliably detected at a 72-75% correct level of performance.
These measures of change will be evaluated baseline to 6-months post-stroke, then 6- to 12-months post stroke, and baseline to 12-months.
\*\*NOTE: Our protocol allows for a +1 month variance for all timepoints.
Trial Locations
- Locations (1)
University of Rochester
🇺🇸Rochester, New York, United States