Determining abnormal interocular latencies of multifocal visual evoked potentials

Donald C. Hood, Xian Zhang, Christopher Rodarte, Bo E. Yang, Nitin Ohri, Brad Fortune, Chris A. Johnson

Research output: Contribution to journalArticlepeer-review

30 Scopus citations


Purpose: To describe methods for measuring interocular latency differences of multifocal visual evoked potentials (mfVEP) and for determining regions with abnormal interocular latencies in patients. Methods: The mfVEPs from 100 individuals with normal visual fields and normal fundus examinations were analyzed. Individuals ranged in age from 21.6 to 92.4 years. The stimulus was a 60 sector, pattern-reversing dartboard display. Each sector had 16 checks, 8 white (200 cd/m2) and 8 black (< 1 cd/m2). Interocular latency was measured as the temporal shift producing the best cross-correlation value between the corresponding responses of each eye. The 'corrected interocular latency' was defined as the difference between this shift and the mean interocular latency (shift) for a particular sector and recording channel. Results: The variability of the corrected interocular latency decreased as the signal-to-noise ratio (SNR) of the mfVEP responses increased. For example, the 95% confidence intervals decreased from over 16 ms to under 4 ms as SNR increased. Grouping and summing the responses also lead to an increase in SNR and a decrease in the confidence interval. The results of various cluster criteria were also derived. A cluster criterion (e.g. two or more contiguous points within a hemisphere exceeding a given confidence interval), can serve to increase the specificity for detection of eyes or individuals with abnormal interocular latencies. For example, while 21% of the eyes had 3 or more points exceeding the 5% confidence interval, only 1.8% of the eyes had a cluster of 3 or more of these points. Finally, interocular latency was only weakly correlated with age (r = 0.26). Conclusion: In testing for abnormalities in interocular latencies, the confidence interval should be based upon the SNR of the response. Grouping and summing responses to increase SNR or employing a cluster test may also prove useful.

Original languageEnglish (US)
Pages (from-to)177-187
Number of pages11
JournalDocumenta Ophthalmologica
Issue number2
StatePublished - Sep 2004
Externally publishedYes


  • Electrophysiology
  • Latency
  • Multifocal visual evoked potential
  • VEP

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems
  • Physiology (medical)


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