Figure 1.

Representative eye movement recordings from a subject with DVD. Red line signifies right eye, blue line signifies left eye. U, upward position; D, downward position. Four layered horizontal panels (A–D) depict changes in DVD (as demonstrated by changing distances between blue and red tracings) in the order that the tests were performed. (A) Alternate occlusion without fixation (monocular darkening). The VOG tracing shows a baseline left hyperdeviation (blue line higher) with mild superimposed DVD caused by isolated luminance disparity. (B) Alternate increased luminance without fixation (monocular flashlight). The VOG tracing shows a lesser left hyperdeviation (relative left hypodeviation) with increased luminance to the left eye than with increased luminance to the right eye. (C) Alternate occlusion with fixation in darkness (crossbar). The VOG tracing shows baseline right hyperdeviation with a hyperdeviation of either eye when that eye is occluded. (D) Alternate occlusion with fixation. The VOG tracing shows baseline right hyperdeviation with a hyperdeviation of either eye when that eye is occluded.