Vergence endurance test: A pilot study for a concussion biomarker

Chang Yaramothu, Lynn D. Greenspan, Mitchell Scheiman, Tara L. Alvarez

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


The Vergence Endurance Test (VET), a quantitative and objective eye movement assessment, was utilized to differentiate control from concussed subjects. Nine symptomatic concussed (2 male; 30.8 ± 11 years) and 9 asymptomatic control (6 male; 25.1 ± 1.4 years) subjects participated in the VET. Symmetrical disparity vergence step targets were presented with and without visual distractors. A masked data analyst measured vergence latency, peak velocity, response amplitude, settling time, and the percentage of trials which contained blinks. A Binocular Precision Index (BPI) and a Binocular Accuracy Index (BAI) were calculated to quantify the changes that occur in the vergence parameters over the duration of the VET. Convergence and divergence peak velocity, divergence response amplitude, the percentage of trials that contained blinks during the transient portion of the response, and the BAI were significantly (p < 0.05) different between the concussed and the control subjects. For these parameters, the BAI and divergence response amplitude yielded the greatest accuracy, 78%, in their ability to discriminate between the groups. The VET objectively measures the change in vergence performance over time and shows promise as a method to diagnose a concussion. Future studies will determine whether the VET can be used to assess the extent of natural recovery and the effectiveness of therapeutic interventions.

Original languageEnglish (US)
Pages (from-to)2200-2212
Number of pages13
JournalJournal of Neurotrauma
Issue number14
StatePublished - Jul 15 2019

All Science Journal Classification (ASJC) codes

  • Clinical Neurology


  • concussion biomarker
  • objective concussion metric
  • post-concussion syndrome
  • vergence distractors
  • vergence eye movements


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