Inclusion Criteria:  Subjects between 18 and 80 years of age. No known prior history of retinal disease. Able to participate in a clinical eye examination setting. Able to consent. Subjects receiving standard of care carotid duplex ultrasounds.  Exclusion Criteria:  Known ophthalmologic disease (e.g. glaucoma, macular degeneration, ocular injury) other than corrected refractive error. Lack of capacity to provide informed consent. Subjects younger than 18 years of age or older than 80 years of age. History of stroke or acute loss of vision. Unable to participate in a clinical eye examination setting.