Hemianopia refers to loss of vision in one half of the visual field of both eyes, most commonly on the right side. Causes of hemianopia include injury to the brain (temporal or occipital lobe) or optic nerve pathways from accident, infection, stroke, or tumor. Hemianopia may also affect the upper or lower halves of the visual field. In the simulations below, normal vision is depicted on the left, and Hemaniopia is depicted on the right.