New Aspects of Dissociated Vertical Deviation

Sandra Tait, DipAppSc (Cumb), DOBA

Dissociated vertical deviation (DVD) is a condition where an eye deviates upwards upon reduction of illumination. The precise characteristics, differential diagnosis and aetiology of this condition however remain very confusing.
Forty-five patients with hyperdeviation under cover were divided into two groups:
1) those with marked updrift
2) those with small updrift
and reviewed with special reference to optokinetic nystagmus (OKN) and the visual evoked response (VER) in an effort to clarify thoughts on this condition.
Results indicate that a high percentage of patients with DVD show asymmetry of monocular OKN possibly indicating anomalies of visual fibre projection as evidenced by abnormalities on the VER. OKN may therefore be a useful and simple clinical test to assess the presence of DVD.