Visual Perceptual Learning for the Treatment of Visual Field Defect

Inclusion Criteria: * Age 19-80 years * Brain damage-induced visual field defect * At least 6 months after brain lesion * Minimum of 4 testing locations, where measured threshold ≤ 20dB * Verified visual pathway damage using CT or MRI * K-MMSE(Korean Mini Mental Status Examination) score ≥ 24 * Visual acuity equal or better than 20/40 * Able to use the investigational device * Patient/legally authorized representative has signed the informed consent form Exclusion Criteria: * Unreliable Humphrey visual field test (any of fixation loss, false positive, false negative ≥ 20%) * Complete hemianopsia with sensitivity of the whole hemifield ≤ 3 dB * Epilepsy, photosensitivity, Parkinson's disease * Bilateral visual field defect * Hemispatial neglect * Ophthalmologic disorder that may interfere the trial * Inability to discontinue psychostimulants such as methylphenidate, modafinil, and amphetamine. * Candidate for carotid endarterectomy or stenting * Received ophthalmologic surgery within 3 months, except for the cataract surgery * Pregnant or breast feeding * Participating in other clinical trial * Any other condition that, in the opinion of the investigator, precludes participation in the trial