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correlation between DVA and ball-catching perfor-mance and an absence of significant correlation between DVA and SVA8). In healthy young adults, those who engage in sports activities were found to have better DVA than those who do not9).In Japan, the relationship between KVA and the batting ability of baseball players was reported at the annual meeting of the Japanese Society of Physical Education in 197110). However, there were no reports on the relationship of KVA with sports for the next 20 years. In 1992, Ishigaki et al. reported that in top-level Japanese basketball, volleyball, soccer, and baseball players, athletes with a higher competitive ability also had higher KVA11). In 1995, people who played tennis continuously for more than 7 years were reported to have better KVA than those with no sports history12). In addition, at the 1996 annual meeting Japan Society of Physical Education, Health and Sport Sciences, a profes-sional baseball team case study reported that KVA was higher in regular players than in second-unit players when they joined the team13).Studies on KVA at Juntendo University’s School of Sports and Health Science began in 1996 with the DHA study by Sawaki & Yoshigi et al. described in “Effects of DHA and astaxanthin on KVA” below. Sakuma et al. investigated the SVA and KVA of male college track-and-field athletes and found that both SVA and KVA were higher in athletes engaged in steeplechase, jump, and mixed events than in short-, middle-, and long-distance runners and throwers and that SVA and KVA are higher in athletes with higher competitive ability14). Aoki et al. investigated elite male pole vaulters and long jumpers and reported that there was no difference in KVA between pole vaulters and long jumpers and that the top competitive pole vaulters had higher SVA and KVA than the bottom pole vaulters15). In addition, Inoue et al. compared the skeleton athletes competing in international sledding competitions and lower group competing in the Japanese National Championships to find that KVA was significantly higher in the upper group than in the lower group, whereas no difference was seen in SVA16).Factors associated with KVASado et al. examined the SVA and KVA of freshmen of the Faculty of Health and Sports Health Science whose SVA was 1.0 or higher17). The number of subjects was 92 (78 men and 14 women aged between 18 and 20 years). SVA was greater than 1.0, whereas KVA ranged from 0.12 to 1.30. KVA could not be estimated from SVA although there was a weak but significant positive correlation between SVA and KVA (r = 0.486 in the right eye, r = 0.490 in the left eye, and r = 0.384 in both eyes)17).Kohmura et al. determined the association between KVA and reaction time. The reaction time, often used in sports science, reflects the ability to identify and respond quickly to visual cues. However, the correlation between KVA and reaction time was not apparent18, 19). Yoshigi et al. also analyzed the relationship between KVA and each component of visual-evoked potential and found a significant correlation between KVA and the peak latency of visual-evoked potentials; the better the KVA, the shorter the peak latency20).Studies have been reported on the effects of training on KVA in baseball players. Kohmura et al. conducted an 8-week training experiment wherein college baseball players were trained to look at the ball at the batter’s box or to use commercially available software for visual function training. KVA was not improved by either training although some effects on visual function were observed21). A subsequent study with junior high school students also revealed that training did not improve KVA22).Kohmura et al. studied 867 men and women aged 8-17 years and reported that DVA developed grad-ually with age, but KVA did not change from age 8 to 17 years23). Therefore, KVA is expected to reach almost the same level as adults by the age of 8 years23).As described above, KVA has a large individual variation, may not be improved by training, and matures up to 8 years old, KVA could be available for finding talent in the junior period in sports.Sports and age-related decline of KVANakamura et al. compared young and elderly kendo players (n = 30) with age-matched nonath-letes (n = 30) and found that KVA significantly decreased with age, whereas contrast sensitivity, eye movement, and instantaneous visual acuity were not affected by age or exercise habits24). At the same time, kendo players had a higher KVA than nonathletes (p < 0.01) when comparing ten young subjects each24). Age-related decline in 389