Hemianopsia

In medicine, a hemianopsia is a neurological sign (medical) on physical examination that is "oartial or complete loss of vision in one half of the visual field(s) of one or both eyes."

Classification
Subtypes include:
 * Altitudinal hemianopsia, "characterized by a visual defect above or below the horizontal meridian of the visual field."
 * Homonymous hemianopsia "refers to a visual defect that affects both eyes equally, and occurs either to the left or right of the midline of the visual field."
 * Binasal hemianopsia "consists of loss of vision in the nasal hemifields of both eyes."
 * Bitemporal hemianopsia is the "bilateral loss of vision in the temporal fields."
 * Quadrantanopsia "refers to loss of vision in one quarter of the visual field in one or both eyes."