Measuring Relative Afferent Pupillary Defect

The goal of this prospective reliability study is to test the effectiveness of a commercially available, off-the-shelf virtual reality head-mounted display (VR HMD) and machine learning (ML) algorithms in detecting Relative Afferent Pupillary Defect (RAPD) in a group of subjects with known RAPD and another group with no known RAPD. The main questions it aims to answer are: * Does the use of the VR HMD and ML to replace the standard of care swinging flashlight test provide a more reliable and objective pupil measurement to detect RAPD? * Can RAPD be detected by the VR HMD and ML algorithms at an earlier stage than the standard of care swinging light test? Participants will be asked to undergo the standard of care swinging flashlight test, have their pupils manually measured, then have the test repeated using the VR HMD and ML. Researchers will compare the measurements taken manually, following the standard of care swinging light test and those recorded by the VR HMD and ML to help answer the above questions.

Inclusion Criteria: * Age 18 - 85 * 60 patients with known RAPD. * 60 patients with no known RAPD * May be diagnosed with a vision disorder such as glaucoma, diabetic retinopathy, unilateral or asymmetrical disease of the retina or other degenerative ocular diseases * Referred to study by treating eye doctor * Volunteered to participate in study * UTMB clinic patients * Not belonging to an identified vulnerable population Exclusion Criteria: * Younger than 18; older than 85 years of age * Not a UTMB clinic patient * Belonging to an identified vulnerable population * Participants with discomfort using glasses * Experience discomfort using VR HMD device * Participants with history of congenital pupil defects, traumatic pupils * Those whose pupils were dilated during the standard of care examination deemed by treating eye doctor not to be eligible to participate in study * Participants who do not follow study directions and/or safety procedures given by investigators or lab assistants * Participants who do not speak English to prevent a communication error during the informed consent process