dissociated vertical deviation

Dissociated vertical deviation (DVD) is an upward drift of either eye, seen spontaneously in a patient who is fatigued or daydreaming or after a cover interrupts fusion.¹ When the cover is removed, the elevated eye moves slowly down to primary position without a corresponding downward movement of the fellow eye.^1,2 The drifting eye also extorts, and the condition is usually bilateral.²

DVD differs from an ordinary hypertropia. In a right hypertropia, the right eye is elevated while the left eye fixates, or the left eye is depressed while the right eye fixates.¹ In DVD, either eye elevates as the fellow eye fixates.¹ A dark red glass separates the two. A patient with DVD places the red image below the fixation light whichever eye the glass covers, while in other cyclovertical deviations the red image lies above or below the light depending on which eye fixates.¹