VEP characteristics in children with achiasmia, in comparison to albino and healthy children

Achiasmia is a rare disorder of visual pathway maldevelopment that can show diverse clinical and magnetic resonance imaging spectra. The aim of this study was to define the characteristics of visual evoked potentials (VEPs) that differentiate abnormal optic-nerve-fibre decussation in children with achiasmia versus children with albinism and healthy children. In four children with achiasmia, the following VEP characteristics were studied and compared to children with ocular albinism and with healthy control children: (a) flash and pattern onset VEP interhemispheric asymmetry; (b) flash N2, P2 and onset C1 amplitudes and latencies; (c) interocular polarity differences in interhemisphere potentials; and (d) chiasm coefficients (CCs). In the children with achiasmia, VEPs were related to an absence of or reduced optic-nerve-fibre decussation at the chiasm and showed: ipsilateral asymmetry, significantly higher VEP amplitudes over the ipsilateral hemisphere ( p