Overview

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.

Eligibility

Cortically Blind Subjects

Inclusion

• 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.
• Able to fixate on visual targets reliably for 1000ms
• Must have a home computer (desktop or laptop) and reliable internet access
• Willing, able, and competent to provide informed consent
• Normal cognitive abilities, able to understand written and oral instructions in English, and competent and responsible adults in order to complete the visual training at home, independently, as instructed, for several months.

Exclusion

• Past or present eye disease interfering with visual acuity
• BCVA worse than 20/40 in either eye
• Damage to the dorsal Lateral Geniculate Nucleus
• Diffuse whole brain degenerative processes
• History of traumatic brain injury
• Any other brain damage deemed by study staff to potentially interfere with training ability or outcome measures
• Documented history of drug/alcohol abuse
• Currently taking neuroactive medications which would impact training, as determined by PI
• Presence of cognitive or seizure disorders
• One-sided attentional neglect
• Subjects who lack the competence or are otherwise unable to perform the visual training exercises as directed.

Control Subjects (n = 50)

Inclusion

• Between 21 and 80 years of age
• Report no history of neurological disorder.
• Competent and responsible, as determined by the Principal Investigator.

Exclusion

• Presence of damage to the visual system
• Presence of an active disease process involving their nervous system.
• Cognitive or seizure disorders
• Best corrected visual acuity worse than 20/40 in either eye
• Presence of vision field loss from ocular disease or disorder