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.