Evidence of Abnormal Optic Nerve Fibre Projections in Patients with Dissociated Vertical Deviation (DVD) – A Preliminary Report

Anne Fitzgerald, DipAppSc (Cumb), DOBA

Abnormal optic nerve pathways can be demonstrated by testing half field checkerboard VER’s. This method has been used to detect abnormal optic nerve fibre projections in human albinos, a group who also have anomalous nystagmoid movements.
Patients with DVD have recently been observed to have abnormal nasotemporal OKN (Mein 1982). The hypothesis that these patients also have abnormal visual pathway projections was tested.
Patients with DVD (both unilateral and alternating), congenital esotropes without DVD and normal subjects were investigated. Results showed a very high incidence of abnormal VER recordings in patients with DVD while recordings from congenital esotropes and the control group were normal. As well as demonstrating abnormal optic nerve fibre pathway projections, the VER’s showed a large increase in latency in all patients with DVD which was not present in the other two groups studied. These results occurred regardless of visual acuity or amblyopia in the eyes tested.
The high correlation between VER abnormalities and naso-temporal OKN anomalies indicates the importance of the latter in diagnosing DVD.
The possible significance of abnormal pathways in the presence of a DVD is discussed.