## 4 Discussion  
This study had two main findings. Firstly, a single multicomponent physiotherapeutic intervention of a 3D-based VT program with FFR generated by auditory frequency entrainment, and bilateral orbital ES for 30 min, improved visual acuity among schoolchildren compared with a control sham intervention or 3D-based VT only. Secondly, the 4-week application of the multicomponent physiotherapeutic intervention VT-FFR-ES (30 min/day, 3 days a week) significantly improved refractive error, as measured using spherical equivalents, compared with the control. Myopia is a common problem in schoolchildren [1], and efficacious public health interventions are urgently warranted to prevent or delay the progression of myopia in schoolchildren. The most effective strategy for controlling myopia has yet to be identified [29]. Nonpharmacological or noninvasive ES interventions for treating myopia have been inconclusive. A meta-analysis between outdoor time and reducing the risk of developing myopia, a notable protective effect of outdoor time, was found for incident myopia in clinical trials and longitudinal cohort studies, and prevalent  
Figure 4: Identity plot between pre- and post-test spherical equivalents after chronic VT-FFR-ES intervention. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & \multicolumn{2}{c}{**Control Group**} & \multicolumn{4}{c}{**VT-FFR-ES**} \\ \hline \multirow{2}{*}{**Before**} & \multirow{2}{*}{**After**} & **Change in** & \multirow{2}{*}{**Before**} & \multirow{2}{*}{**After**} & **Change in** & \multirow{2}{*}{**\(p\)***\({}^{*}\)**} \\  & & & **Refraction** & & & & **Refraction** & \\ \hline \multirow{2}{*}{
\begin{tabular}{c} Spherical \\ equivalent (D) \\ \end{tabular} } & \multirow{2}{*}{\(-2.56\pm 1.79\)} & \multirow{2}{*}{\(-2.66\pm 1.91\)} & \multirow{2}{*}{\(-0.10\pm 0.26\)} & \multirow{2}{*}{\(-2.59\pm 1.88\)} & \multirow{2}{*}{\(-2.38\pm 1.72\)} & \multirow{2}{*}{\(0.21\pm 0.32\)} & \multirow{2}{*}{\(<\)0.001} \\  & & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Refractive error between chronic Control and VT-FFR-ES interventions (n = 50 eyes in each group). myopia in cross-sectional studies (reducing the risk to 46%, 43%, and 4%, respectively). The pooled results of outdoor time in clinical trials showed that there was a reduced myopic shift in both myopes and non-myopes (\(-\)0.30 D), and compared with a control group (weighted mean difference = \(-\)0.30 D, 95% CI = \(-\)0.18 to \(-\)0.41), over a 3-year follow-up period. However, only in among myopes, no dose-response relationship was found in the analysis between time outdoors and myopic progression (R\({}^{2}\)= 0.00064). Increased outdoor time is effective in preventing the onset of myopia and slowing the myopic shift. Unexpectedly, outdoor time was not an effective strategy in slowing progression in the eyes that were already myopic [30]. Therefore, VT is considered an eye exercise training for preventing from myopic progression, which is responsible for changing the focus of the eyes. Another nonpharmacological therapy that was tested was VT with the simultaneous use of soft lenses in 14-22-year-old patients with myopia [18]. The results revealed that VT significantly affected shorter distant viewing times; however, this outcome of the evaluation differed from ours (visual acuity and spherical equivalent). One study observed that daily VT-based eye exercises for 6 weeks significantly improved visual acuity in 12-15-year-old girls with myopia [31]. This result partially supported our result for a 4-week intervention of VT-FFR-ES for 30 min/day, 3 days a week. An information and communication technology (ICT)-based VT program involving a head-mounted wearable device in young adults (22.8 \(\pm\) 3.8) stimulated the contraction and relaxation of ciliary muscles of the eye and improved refractive errors by 0.44 \(\pm\) 0.35 D in a VT group compared with a comparative group [32]. VT involves the contraction and relaxation of the ocular ciliary muscles, which, in turn, improves vision.