Dissociated vertical deviation.

Dissociated vertical deviation (DVD) is a poorly understood vertical deviation which may remain latent (compensated) or manifest (decompensated). The deviation may be symmetrical or asymmetrical, and small or very large, measuring more than 20 prism diopters. DVD may occur alone or in combination with a true hyperdeviation. Bilateral superior rectus recession of 9-16 ml is effective. Asymmetrical DVD is treated with asymmetrical surgery.