Quantitative Analysis of Horizontal Eye Movements and Concentration of Serum and Plasma BDNF Level Before and After Vision Training

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    • Department of Ophthalmology, Juntendo University Faculty of Medicine
    • Faculty of Health and Sports Sciences, University of Tsukuba


<p><b><i>Purpose: </i></b>Eye movements are important factors for dynamic visual acuity (DVA) that refers to the ability to perceive fine details of a moving object. When tracking a moving visual stimulus, we often combine smooth eye movements with catch-up saccades. The velocity of saccade eye movements (up to 500-600 deg/s) is much faster than smooth pursuit (usually less than 50 deg/s). Even though a tracking ability using these two kinds of eye movements is thought to play a critical role in DVA, it is still uncertain whether better DVA is associated with an ability of catch-up saccades. The first purpose of this study was to quantitatively clarify the effects of vision training on DVA and eye movements. Therefore, we repetitively measured the eye movements during DVA training and attempted to determine the effects of visual training on saccade eye movements. The second purpose was to assess the concentration of serum and plasma brain-derived neurotrophic factor (BDNF) level before and after vision training. BDNF is a member of the neurotrophin family of growth factors, which are related to the canonical Nerve Growth Factor. Previous studies have reported that moderate intensity exercise leads to increase in BDNF. However it is unknown whether BDNF level is correlated with eye movements. Therefore, we examined the correlation between BDNF level and eye movement parameters.</p><p><b><i>Methods: </i></b>DVA was evaluated by a moving visual target (Landolt ring) that was projected on the front screen (HI-10; Kowa, Japan). Eye movements were detected using a video based eye tracking system (Eye Link1000; SR research, Canada). We have performed measuring DVA in five subjects (mean age; 19.0±2.6, age range; 19 to 21 years old) and analyzed saccades eye movements quantitatively using custom analytical software (Matlab; Mathworks Inc., USA). Subjects were seated in front of a screen and put their jaw on a chin supporter of our device to stabilize the head. The subjects were asked to follow the Landolt ring moving across in front of their visual field and judge the direction of the slit. We analyzed saccade latency (msec), peak velocity (deg/sec), error (deg) and a correct response rate (%). The Landolt ring moved either from right to left or left to right with constant speed of 300 deg/s. A total of eight measurements were performed for each subject. We took blood samples from each subject before and after vision training and checked serum and plasma level of BDNF.</p><p><b><i>Results: </i></b>Our results demonstrated that saccade latency and error showed significant decreases and the correct response rate increased after training for five subjects. Especially for the result of correlation analysis, the correct response rate showed a correlation coefficient of 0.63 (p=0.021), indicating a stronger correlation than the other three parameters. In contrast, saccade peak velocity showed different results among subjects. For three subjects, the velocity increased while two subjects showed a decrease in velocity after training. The results of the analysis showed a significant positive correlation of the concentration of plasma BDNF level with velocity and the correct response rate. However, the results showed a significant negative correlation of the concentration of plasma BDNF level with latency and error. It was also revealed that the results of plasma and serum BDNF level were contrary to each other.</p><p><b><i>Conclusion: </i></b>Our study provided several lines of evidence showing that saccade eye movements, such as latency, error and peak velocity changed after vision training. Since our results showed that visual training improved DVA, better DVA could be associated with the tracking ability using catch-up saccades. We were also able to clarify that the plasma and serum BDNF possibly affected actual eye movements.</p>


  • Juntendo Medical Journal

    Juntendo Medical Journal 62(Suppl.1), 77-77, 2016

    The Juntendo Medical Society


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