Vergence Endurance Test: A Pilot Study for a Concussion Biomarker

Abstract

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.

Reflexive Fusional Vergence and Its Plasticity Are Impaired in Convergence Insufficiency

“…This is consistent with recent results that have characterized more rapid fatigue in the reflexive fusional convergence responses of patients suffering from traumatically induced CI. 31 A second aim of this study was to test the hypothesis that attenuated reflexive vergence responses would be unable to recruit larger motor responses to increased stimulus demands, thus suggesting saturation of the reflexive fusional response mechanism. The similarities between the divergence data in each group and the convergence data in the CI group support this hypothesis.…”

“…This is consistent with recent results that have characterized more rapid fatigue in the reflexive fusional convergence responses of patients suffering from traumatically induced CI. 31 …”

“…7,[27][28][29][30] In traumatically acquired CI, these convergence responses fatigue quickly, showing poor endurance. 31 This is in addition to the classic clinical presentation of a reduced near point of convergence (NPC), large dissociated exophoria at near and reduced positive relative vergence. 2,32,33 Relative fusional vergence ranges are a clinical metric of the underlying plasticity of tonic vergence innervation.…”

Reliability of Frontal Eye Fields Activation and Very Low-Frequency Oscillations Observed during Vergence Eye Movements: an fNIRS Study

“…All participants, had normal ocular health using methods described in previous vergence oculomotor studies which includes a battery of oculomotor tests 44-49 . experimental setup. A haploscope system was used to stimulate vergence disparity, similar to the one shown in previous studies which keeps accommodative vergence constant 45,50 . Symmetrical disparity vergence step responses were presented to each eye via two separate monitors.…”

Target eccentricity and form influences disparity vergence eye movements responses: A temporal and dynamic analysis

“…The impact of VR on eye movements is only beginning to be investigated [ 2 ]. Applications in VR range from pain reduction interventions [ 3 , 4 ] to surgery simulation tools [ 5 – 7 ] to vision therapy techniques [ 8 , 9 ]. Hence, VR has enormous potential to be impactful to our society for a variety of applications.…”