e. Conversion disorder
( Victor, pp 265–266.) Tunnel vision must be distinguished from concentric constriction. In the latter, the area perceived enlarges as the test screen is moved farther away from the patient, but the overall visual field is always smaller than the normal visual field. Concentric constriction associated with optic atrophy may develop with neurosyphilis. Tunnel vision, on the other hand, is characterized by the patient reporting the same size field even as the test screen is removed further away. Tunnel vision is not a physiologic pattern of visual loss, and should suggest either conversion disorder or malingering. Significant spiraling of the visual field, in which repeat testing of the same part of the visual field during the same examination leads to a successively smaller field each time, similarly may reflect conversion or malingering, although stress or panic may lead to mild effects of this sort.