Vision Loss Impact on Navigation in Virtual Reality

Cortically Blind Group: Inclusion Criteria: * Residents of the United States or Canada * Presence of one-sided stroke or stroke-like damage to primary visual cortex or its immediate afferent white matter sustained within the specified age range of 21 - 75 years (verified by MRI and/or CT scans) * Reliable visual field defects in both eyes (homonymous defects) as measured by Humphrey or equivalent perimetry. * Willing, able, and competent to provide their own informed consent * Cognitively able, responsible to understand written and oral instructions in English * Emmetropic or else wear corrective contact lenses inside the virtual reality headset Exclusion Criteria: * Those who have never driven or earned a drivers' license * Past or present ocular disease interfering with visual acuity * Best corrected visual acuity (BCVA) worse than 20/40 in either eye * Sustained damage to the dorsal lateral geniculate nucleus * Presence of diffuse, whole-brain degenerative processes * Presence of brain damage deemed by study staff to potentially interfere with outcome measures * History of traumatic brain injury * Documented history of drug/alcohol abuse * Diagnosis of cognitive or seizure disorders * Diagnosis of one-sided attentional neglect Control Group: Inclusion Criteria: * Normal or corrected-to-normal vision, who are between the ages of 21 and 75 years of age, roughly matched to the age of CB subjects enrolled above * Competent and responsible, as determined by the Principal Investigator * Willing, able, and competent to provide their own informed consent * Normal cognitive abilities, be able to understand written and oral instructions in English * Emmetropic or else wear corrective contact lenses inside the virtual reality headset Exclusion Criteria: * Subjects who have never driven or earned a drivers' license * BCVA worse than 20/40 in either eye * Presence of vision loss from ocular diseases or disorders * Presence of a visual field defect * Inability to wear corrective contact lenses inside the virtual reality helmet if required to see clearly * Subjects with a history of neurological disorders * Subjects with a history of TBI * Persons who lack the competence or are otherwise unable to perform the visual testing as directed.