A low-cost video-oculography system for vestibular function testing

Abstract

In order to remain in focus during head movements, vestibular-ocular reflex causes eyes to move in the opposite direction to head movement. Disorders of vestibular system decrease vision, causing abnormal nystagmus and dizziness. To diagnose abnormal nystagmus, various studies have been reported including the use of rotating chair tests and videonystagmography. However, these tests are unsuitable for home use due to their high costs. Thus, a low-cost video-oculography system is necessary to obtain clinical features at home. In this paper, we present a low-cost video-oculography system using an infrared camera and Raspberry Pi board for tracking the pupils and evaluating a vestibular system. Horizontal eye movement is derived from video data obtained from an infrared camera and infrared light-emitting diodes, and the velocity of head rotation is obtained from a gyroscope sensor. Each pupil was extracted using a morphology operation and a contour detection method. Rotatory chair tests were conducted with our developed device. To evaluate our system, gain, asymmetry, and phase were measured and compared with System 2000. The average IQR errors of gain, phase and asymmetry were 0.81, 2.74 and 17.35, respectively. We showed that our system is able to measure clinical features.

Measurement and Analysis of Eye Movements Performance to Predict Healthy Brain Aging

“…9 shows the latencies measured in the vertical tests while (8) shows the linear estimation of the values (going toward the stimulus and going back to the center of the screen). Comparing (7) with (8), the behavior of latencies in healthy volunteers seems to be analogous: linear increase and a higher slope with the age in the returning saccades.…”

“…8 presents the mean values of the horizontal latency during the test (go to the stimulus and back to the center). Using a linear estimation model to evaluate the progression of the values, it is observed that the latency of saccadic movement is higher with aging in both, horizontal and vertical movements (7).…”

“…y h go = 187.16 + 0.55x y h_back = 162.22 + 0.89 (7) Fig. 9 shows the latencies measured in the vertical tests while (8) shows the linear estimation of the values (going toward the stimulus and going back to the center of the screen).…”

“…The VOG systems consist of, at least, one camera that records the eye/s movement. Some authors suggest that the VOG system is replacing EOG because of its accuracy and simplicity [7]- [9]. Therefore, thanks to technological improvements, the EM is started to be measured quantitatively in an increasing number of medical centers.…”

Prototipo de video frenzel-video head impulse test de bajo coste

“…Park et al, en el año 2017 13 desarrolló un video oculográfico de bajo coste. Es un aparato que es capaz de detectar los movimientos sacádicos.…”