To the best of our knowledge, this is the first study that provides detailed information on the effects of traditional Chinese eye exercises of acupoints in school children. There was one key finding in the current study. The seriousness of attitude towards performing these eye exercises and acquaintance with the acupoints were associated with a lower CISS score, i.e., less ocular-based near vision symptoms.
Less myopic refractive error was observed in children who performed the eye exercises of acupoints seriously as compared to those who did not. However, this protective effect was lost after two significant confounders, namely age and parental refractive error, were adjusted. Furthermore, refractive error of the children did not tend to be relatively more hyperopic as time for performing the eye exercises of acupoints per week increased. This finding may undermine the protective effect of the eye exercises of acupoints on the reduction of myopic refractive error.
The refractive error was significantly more myopic in children who performed the additional eye exercises of acupoints after school hours. There could be two possible reasons underlying this unexpected finding. First, children with a more myopic refractive error may have had greater determination, or were under greater psychological pressure, to do so from their teachers and/or parents to draw less attention to the problem of myopic progression, and furthermore to prevent yet further increases. Second, performing the eye exercises of acupoints after school involved less actual time than when performed in school (percentage of those performing the eye exercises of acupoints twice per day or more: 69.4% vs. 85.8%). However, quality of the eye exercises of acupoints performed outside of school hours could not be guaranteed without supervision.
In the present study, the prevalence of myopia was not associated either with one’s attitude towards performing the eye exercises of acupoints or acquaintance with the related acupoints. However, these results should be considered along with certain limitations of the study design. First, as mentioned earlier, children with a greater myopic refractive error may be more determined to perform the eye exercises of acupoints, and they may also have a better understanding of the eye exercises’ acupoints. Second, urban Chinese children are exposed to high risk factors for causation of myopia, such as increased near work activity hours, less outdoor activity hours, a crowded living environment, and a higher probability of having myopic parents [28, 29]. Thus, the overall effect of these eye exercises on reduction of refractive error by only 5–10 minutes of exercise time each day in this highly susceptible population appeared to be negligible. Longer and more intensive eye exercises of acupoints may thus be necessary to be effective. Hence, well-designed randomized controlled trial (RCTs) would be necessary to investigate the effect of different durations of the eye exercises of acupoints on reducing myopia.
In the current study, children who performed the eye exercises of acupoints seriously, who followed the school broadcast when performing the exercises, and who were acquainted with the exercises acupoints, tended to have a lower CISS score even after adjusting for the confounders. Considering the linkage and correlation between accommodation, vergence, and refractive error [30, 31], a further multiple regression model with children’s refractive error adjusted was employed, with it yielding similar results. However, the reduction in symptoms was relatively small (CISS score reduced 2.5-3.5 points). Borsting et al. reported that the CISS score was 30.8 in children with convergence insufficiency; children with a CISS score of 16 or higher are considered to be symptomatic . The CISS score of the current study was approximately 14, consequently less than in children with convergence insufficiency. Hence, there may be a floor effect for the CISS score to reduce yet further. Our current findings suggested that the eye exercises of acupoints modestly reduced these ocular-based near symptoms in Chinese urban children with high normal scores. It would be interesting to determine if the eye exercises of acupoints would have more effect on relief of near symptoms in children with convergence insufficiency or a higher CISS score. Furthermore, the placebo effect of the eye exercises may not be excluded, since there was no control group in the current study.
The eye exercises of acupoints mildly reduced the ocular-based near symptoms. However, little is currently known about the mechanisms underlying reduction of these symptoms. It has been proposed that acupuncture at these vision-related acupoints increased blood flow to the cerebral and ocular vasculatures (including the choroid) [32–34], thus leading to metabolic changes in the central and peripheral nervous system [34–36]. Although the effect of such massage in these vision-related acupoints may be less than acupuncture itself, it is likely that the effects of the eye exercises of acupoints on visual symptoms is due to multiple mechanisms. In addition, simple cessation of near work to perform the eye exercises of acupoints provides a brief rest period that itself may reduce the visual fatigue effects .
There are potential limitations of the present study. First, the children were enrolled consecutively at the baseline of the Beijing Myopia Progression Study. Hence, results of the current study may not be generalisable to the entire population of Beijing children across the educational spectrum. Longitudinal data would provide more convincing evidence. Second, the results of this study would be stronger, with either a control or comparative group. Finally, further studies, especially well-designed RCTs, with a larger sample size and different eye exercise schedules, are warranted to understand better the dose-effect of these eye exercises of acupoints on myopia and the related visual-based near symptoms.