Eyetracking-enhanced VEP for nystagmus

Carter, Perry, Shawkat, Fatima, Self, James, Lee, Helena, Keeling, Eloise and Dunn, Matt ORCID: https://orcid.org/0000-0002-0295-2182 2023. Eyetracking-enhanced VEP for nystagmus. Presented at: 2023 ARVO Annual Meeting, New Orleans, LA, United States, 23-27 April 2023. Investigative Ophthalmology & Visual Science. , vol.64 (8) Association for Research in Vision and Ophthalmology,

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Abstract

Purpose : Visual evoked potential (VEP) testing is an essential first stage in the diagnostic workup of patients with infantile nystagmus (IN). VEPs are an important factor in the diagnosis of albinism, which accompanies IN in ~28% of cases, as well as chiasmal, optic nerve and neurometabolic disease that can all present with IN. VEPs are also used to assess prognostic visual ability in cases of retinal dystrophy and optic nerve disease. Despite being used regularly in those with IN, VEP testing requires patients to keep the eyes still; something that people with IN naturally cannot do. Fixation instability during VEP testing is believed to reduce VEP signal amplitude, and as a result, the reliability of VEP may be reduced in one of the patient groups that needs it the most. This study investigates whether VEP signal quality (amplitude) can be improved in people with IN, by triggering acquisition only during the foveating (slow) periods of the nystagmus waveform. Methods : A novel method of VEP triggering was developed, by recording live eye movements from individuals with IN (using an EyeLink 1000+) and triggering VEP acquisition (with an Espion device) only during foveating periods of the nystagmus waveform (i.e., low velocity). VEP amplitude as acquired using this method was compared to VEPs triggered using continuous (regular, non-gaze-contingent) acquisition. Data were collected in seven patients with IN (pattern onset/offset in all participants, and pattern reversal in three). Full datasets were also collected for comparison in three patients with acquired nystagmus. Results : In patients with IN, VEP signal amplitude is significantly increased by gaze-contingent VEP triggering (mean = 18 µV, as compared to 12 µV under continuous acquisition; p < 0.001). In the three patients with acquired nystagmus, triggering VEPs using eye velocity had no significant effect on VEP amplitude (p = 0.130). Conclusions : Triggering VEP acquisition during foveation periods (based on eye velocity) significantly increases VEP amplitude and therefore has the potential to improve prognostic reliability in people with IN.

Item Type:	Conference or Workshop Item (Paper)
Date Type:	Publication
Status:	Published
Schools:	Optometry and Vision Sciences
Additional Information:	This abstract was presented at the 2023 ARVO Annual Meeting
Publisher:	Association for Research in Vision and Ophthalmology
ISSN:	1552-5783
Funders:	Fight for Sight/Nystagmus Network
Last Modified:	24 Jul 2023 10:00
URI:	https://orca.cardiff.ac.uk/id/eprint/161204

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