A reduced visual pathway response in infantile nystagmus syndrome

J AAPOS. 2021 Feb;25(1):9.e1-9.e6. doi: 10.1016/j.jaapos.2020.09.005. Epub 2021 Feb 16.

Abstract

Purpose: To investigate visual cortical responses in children with infantile nystagmus syndrome (INS) and the potential contribution of foveation periods.

Methods: The medical records of children with INS who had visual evoked potential (VEP) recordings to reversing checkerboards and onset of horizontal gratings were reviewed retrospectively. VEP recordings underwent objective selective averaging for extraction of brief periods having consistent amplitude and timing with the stimulus presentation. VEP amplitude, latency, and signal-to-noise ratios (SNR) were compared to results from published age-matched controls under the same conditions. Relative foveation in INS subjects was determined from the proportion of time a video-oculography recording met eye position and velocity criteria.

Results: A total of 26 children met inclusion criteria. Selective averaging increased VEP amplitude and SNR in INS by 270%-420% compared to standard averaging (P < 0.0001). The INS change in VEP response was greater for reversing checkerboard stimulation than horizontal-grating onset and was significantly greater than that in controls (P < 0.001). Latency was not changed by selective averaging. Relative foveation was correlated with increasing VEP amplitude (P = 0.02) and number of trials chosen for selective averaging (P < 0.01). After selective averaging, relative foveation correlated with VEP amplitude to reversing checkerboards only (P = 0.007).

Conclusions: Nystagmus likely causes a reduced visual cortical response in children with INS. A significantly larger response can be extracted from brief periods during nystagmus eye movements, supporting the hypothesis that the INS visual system generates a larger cortical signal during brief foveation periods.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Child
  • Evoked Potentials, Visual
  • Humans
  • Nystagmus, Pathologic*
  • Retrospective Studies
  • Visual Acuity
  • Visual Pathways*