Training in VNG
What is the Optokinetic Nystagmus Test?
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
