4. Discussion
hand coordination impairment, hand coordination impaired, peripheral visual perception
SECONDARY, CORTEX
The major finding of the present study was that VDT operation temporarily impaired the eye–hand coordination and smooth-pursuit eye movements, and astaxanthin, lutein, and zeaxanthin improved eye–hand coordination impaired by VDT operation. This finding supports the hypothesis that dietary supplementation with astaxanthin, lutein, and zeaxanthin is of benefit in preventing eye–hand coordination impairment caused by VDT. VDT operation has been reported to lead to continuous tension of the ciliary muscle because the time spent looking closely at a terminal is long, leading to a decrease in the amplitude of accommodation [The following were considered concerning the action mechanism of the test food on eye–hand coordination. Astaxanthin consumption has been reported to significantly restore accommodative function [In the present study, the change in MPOD levels between baseline and eight weeks in the active treatment group was significantly higher than that in the placebo group. The macular pigment is composed of lutein and zeaxanthin, and MPOD is used to qualify lutein and zeaxanthin in the macular [In the present study, although consumption of the test food improved smooth-pursuit eye movements impaired by VDT operation at two weeks, there was no observation of the improvement effects of the test food on smooth-pursuit eye movements at eight weeks. This may be because the VDT operation method in this study mainly used saccade eye movements and the range of decrease in smooth-pursuit eye movements induced by VDT operation was too small for accurate evaluation. In addition, saccade and smooth-pursuit eye movements traditionally have distinct neural systems. For smooth-pursuit eye movement, these pathways are composed of a seemingly simple circuit connecting areas in the temporal and frontal lobes of the cerebral cortex with pursuit-related motor regions of the cerebellum [Regarding the QOL questionnaire, for one of the secondary outcomes, there was no observation of improvement effects of the test food. The VAS method is subject to high variability, because individuals often feel differently about questions. Thus, as the number of participants in this study was small, it may not have been accurately evaluated.The test food can contribute to enhancing QOL by suppressing the decline in eye–hand coordination after VDT. Moreover, this study has suggested that test foods can contribute to PC game and sports performance. Previous studies have proposed that strenuous exercise impairs peripheral visual perception by decreasing cerebral oxygenation [Our study had several limitations. First, astaxanthin, lutein, and zeaxanthin are present in daily meals. In this study, we prohibited the participants from consuming health foods or supplements that contained astaxanthin, lutein, and zeaxanthin. However, we did not impose strict dietary restrictions on our subjects, and it is unclear what amount of these ingredients they consumed in their daily diet. Thus, the effects of supplemental astaxanthin, lutein, and zeaxanthin may have been obscured. Second, in this study, the combination of astaxanthin, lutein, and zeaxanthin was designed as the active group rather than astaxanthin or lutein/zeaxanthin alone. Thus, it is unclear whether the effect of the test food on eye–hand coordination is due to additive or synergistic effects. Although we believe that the combination of these nutrients is essential for the effects on eye–hand coordination because of the different mechanisms of action between astaxanthin and lutein/zeaxanthin, further studies are necessary to clarify the mechanisms underlying the beneficial effects of these nutrients.