This project is intended to collect data using standard clinical tests and psychophysics to quantify the effect of visual cortical damage on the structure of the residual visual system, visual perception, spatial awareness, and brain function. The investigators will also assess the effect of intensive visual retraining on the residual visual system, processing of visual information and the use of such information in real-world situations following damage. This research is intended to improve our understanding of the consequences of permanent visual system damage in humans, of methods that can be used to reverse visual loss, and of brain mechanisms by which visual recovery is achieved.
Between 21 and 80 years of age
Residents of the United States or Canada
Unilateral stroke or stroke-like damage to primary visual cortex or its immediate afferent white matter sustained within the specified age range (21-75 years)
Reliable visual field defects in both eyes as measured by Humphrey, MAIA, Goldmann, and/or equivalent perimetry, large enough to enclose a 5-deg diameter visual stimulus.
None
Parallel
Training in the Blind Field
DeviceA computer software and chin-rest necessary to perform visual training will be loaned to each subject to be used at home. Subjects will perform one to two daily training sessions in their home, consisting of 200-300 trials each. The visual task performed repetitively will involve discriminating the direction of motion, the presence of motion, or the orientation of a visual stimulus (either a small cloud of dots or bars) located at a predetermined location in the blind field. The computer program will automatically create a record of patient performance during each home training session. Subjects will train daily (about 40-60 minutes total), 5 to 7 days per week for at least 3 and up to 12 months at a time.
Change in Mean Direction Discrimination Threshold
For each subject, the investigators will measure the change in ability to detect differences in the motion direction of visual stimuli relative to horizontal, measured in degrees of visual angle with respect to the stimulus. These assessments will be based on what can be reliably detected at a 72-75% correct level of performance on our 2AFC task, with task difficulty adjusted on a 3:1 staircase. The degrees of visual angle for the stimulus vary from 90 degrees (fully vertical) to 0.1 degrees (virtually overlapping the horizontal axis). These measures of change will be evaluated baseline and at each subsequent visit to the laboratory; minimally from baseline to 4-6 months, then baseline to 8-12 months from start of training
Change in Mean Direction Discrimination Threshold
For each subject, the investigators will measure the change in ability to detect differences in the motion direction of visual stimuli relative to horizontal, measured in degrees of visual angle with respect to the stimulus. These assessments will be based on what can be reliably detected at a 72-75% correct level of performance on our 2AFC task, with task difficulty adjusted on a 3:1 staircase. The degrees of visual angle for the stimulus vary from 90 degrees (fully vertical) to 0.1 degrees (virtually overlapping the horizontal axis). These measures of change will be evaluated baseline and at each subsequent visit to the laboratory; minimally from baseline to 4-6 months, then baseline to 8-12 months from start of training
Change in Mean Direction Integration Threshold
This will measure the change in ability of subjects to integrate across a range of motion directions measured in degrees of visual angle, with respect to the stimulus. These assessments will be based on what range of motion directions can be reliably integrated at a 72-75% correct level of performance on our 2AFC task, with task difficulty adjusted on a 3:1 staircase. The degrees of visual angle for the stimulus vary from 90 degrees (fully vertical) to 0.1 degrees (virtually overlapping the horizontal axis) . These measures of change will be evaluated baseline and at each subsequent visit to the laboratory; minimally from baseline to 4-6 months, then baseline to 8-12 months from start of training.
Change in Mean Direction Integration Threshold
This will measure the change in ability of subjects to integrate across a range of motion directions measured in degrees of visual angle, with respect to the stimulus. These assessments will be based on what range of motion directions can be reliably integrated at a 72-75% correct level of performance on our 2AFC task, with task difficulty adjusted on a 3:1 staircase. The degrees of visual angle for the stimulus vary from 90 degrees (fully vertical) to 0.1 degrees (virtually overlapping the horizontal axis) . These measures of change will be evaluated baseline and at each subsequent visit to the laboratory; minimally from baseline to 4-6 months, then baseline to 8-12 months from start of training.
Humphrey 10-2 and 24-2 perimetry
The investigators will measure the change in visual sensitivity (measured in decibels) at all locations tested by the system. These measures will be evaluated at baseline and at each subsequent visit to the laboratory; minimally from baseline to 4-6 months, then baseline to 8-12 months from start of training.
Humphrey 10-2 and 24-2 perimetry
The investigators will measure the change in visual sensitivity (measured in decibels) at all locations tested by the system. These measures will be evaluated at baseline and at each subsequent visit to the laboratory; minimally from baseline to 4-6 months, then baseline to 8-12 months from start of training.
Goldmann perimetry
The investigators will measure the change in area of vision (degrees squared) as encompassed by each isopter, measured by one of 3 different light stimuli. The 3 isopters which will be compared are: I2e 1asb, 0.25 mm\^2 I4e 10asb, 0.25 mm\^2 V4e 1000asb, 64 mm\^2 These measures will be evaluated at baseline and at each subsequent visit to the laboratory; minimally from baseline to 4-6 months, then baseline to 8-12 months from start of training.
Goldmann perimetry
The investigators will measure the change in area of vision (degrees squared) as encompassed by each isopter, measured by one of 3 different light stimuli. The 3 isopters which will be compared are: I2e 1asb, 0.25 mm\^2 I4e 10asb, 0.25 mm\^2 V4e 1000asb, 64 mm\^2 These measures will be evaluated at baseline and at each subsequent visit to the laboratory; minimally from baseline to 4-6 months, then baseline to 8-12 months from start of training.
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University of Rochester
Lead sponsor
National Institutes of Health (NIH)
Collaborator
Research to Prevent Blindness
Collaborator
