Training in VNG

What is the Optokinetic Nystagmus Test?

Introductory
10 mins
Video
09 February 2022

Description

This video provides a description of how the Optokinetic test is performed and a short summary of results interpretation. You can read the full transcript below.

 

Optokinetic stimulation

What we have here is an example of optokinetic stimulation, which is a full field stimulation that initiates a checkerboard or striped pattern to induce a corrective eye movement that very much looks like nystagmus.

So, we're generating a nystagmic eye movement that we can measure both going to the right and to the left to assess whether or not the patient is able to initiate those eye movements appropriately and symmetrically.

 

Summary data and results interpretation

Here's an example of some of those recordings that we can see within our software, and this allows us to quantify the slow phase velocity of those eye movements and establish whether we have equal gain, i.e. does the eye move to the correct degree of movement both right and left?

And we can look at this at different velocities. So, we could look at 20 degrees of movement or 40 degrees per second of movement both in the right and left directions. We can also look at the surface velocity of that nystagmus and calculate a symmetric or symmetry value to see whether we have any lesions or any changes that are predominantly moving either to the left direction or to the right direction.

At this point, it's worth mentioning that the optokinetic out of the oculomotor examinations has the least specificity in relation to identifying a central nervous system pathology.

However, as an additional supportive test within the oculomotor examination, we can see where it would show changes potentially both between the pursuit and the optokinetic to see whether we've got consistent findings within our oculomotor examination.

Presenter

Darren Whelan
Darren holds an undergraduate degree in audiology and postgraduate master’s degrees in health science, neurophysiology, and clinical research. His resumé includes several clinical positions in the National Health Service (NHS). Prior to his current occupation as an International Clinical Trainer in the Interacoustics Academy, Darren held a clinical audiology and research scientist role in the UK, where he investigated patients with auditory and vestibular pathology, and managed a portfolio of NIHR adopted research studies. He has been a guest speaker at national and international conventions, enjoys teaching and providing clinical insights on the management of patients with dizziness and is a contributing author on published audiological and vestibular articles. Darren is an adjunct professor at Salus University in the USA, lecturing on the Doctor of Audiology degree.

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