A head-mounted visual stimulator for neurotological examination

Objectives: Presently, the neurotological tests, using visual stimulation, such as optokinetic nystagmus test (OKN), eye-tracking test (ETT) is being widely used for the diagnosis of vertigo or disequilibrium. The problems of these tests are the large size of the visual stimulator and therefore a wide space requirement. Even if a small apparatus is developed, the apparatus itself would be very expensive. In this study, we developed a small visual stimulation test system comprising the virtual visor, which receives an image for visual stimulation from an on-line computer. Methods: Using smooth pursuit and optokinetic stimulation onto a virtual visor we assessed the ENG recording in 20 normal subjects. Result: We found the 30°/s OKN, horizontal eye tracking were adequately stimulated by this technique with reliable results. Conclusion: This new method of smooth pursuit and optokinetic stimulating by a virtual visor is capable of producing reliable results and may be used in the clinical laboratory of vertigo. However, this stimulator also has some limitations, mainly because of the visual angle of the virtual visor stimulator.