Amblyopic deficit beyond the fovea: Delayed and variable single-trial ERP response latencies, but unaltered amplitudes

Éva M. Bankó, Judit Körtvélyes, János Németh, Zoltán Vidnyánszky

Research output: Contribution to journalArticle

3 Citations (Scopus)


Purpose. Amblyopia was first described as a deficit of central vision. However, it has long been debated whether this dysfunction is limited to the fovea or whether extrafoveal vision is also affected, as studies concerning the latter are equivocal. The purpose of the study was to resolve this issue. Methods. We investigated the amblyopic effect on event-related potentials (ERPs) with foveal and perifoveal stimuli, either matched in size based on cortical magnification or presented as large annular stimuli. In two separate experiments we measured ERPs on amblyopic patients and control subjects using face images. Latency and amplitude of averaged ERPs and their single-trial distributions were analyzed. Results. When the fovea was stimulated, latency and amplitude of the early averaged ERP components increased and were reduced, respectively, in the amblyopic compared with the fellow eye. Importantly, perifoveal stimulation also elicited similar amblyopic deficits, which were clearly significant in the case of using cortical magnification scaled stimuli. However, single-trial peak analysis revealed that foveal and perifoveal effects differed in nature: Peak amplitudes were reduced only in foveal stimulation, while latencies were delayed and jittered at both the fovea and perifovea. Event-related potentials obtained from fellow eyes were not significantly different from those of normal observers. Conclusions. Our findings revealed the existence of amblyopic deficits at the perifovea when the stimulated cortical area was matched in size to that of foveal stimulation. These deficits manifested themselves only in the temporal structure of the responses, unlike foveal deficits, which affected both component amplitude and latency.

Original languageEnglish
Pages (from-to)1109-1117
Number of pages9
JournalInvestigative Ophthalmology and Visual Science
Issue number2
Publication statusPublished - Jan 21 2014


  • Cortical magnification
  • ERP
  • P1
  • Single-trial peak detection
  • Visual cortex

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems
  • Cellular and Molecular Neuroscience

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