Also found in: Dictionary, Thesaurus, Medical, Wikipedia.
loss of half of the field of vision; half blindness.
Hemianopsia is described as either multilateral, which is characterized by loss of either the outer or the inner halves of the field of vision, or unilateral (homonymous), in which the same halves of the field of vision (whether right or left) are lost. Hemianopsia occurs with cerebal hemorrhage, cranial injuries, or brain tumors. If the brain tissue is not entirely destroyed, hemianopsia is reversible. The lost field of vision is usually blind to all types of visual sensations, although sometimes perception of the shape of an object, for example, is lost, while perception of color, light, and movement in the same field of vision is preserved. Treatment involves elimination of the primary cause of the hemianopsia.