It seems that it is more specifically violet light [1] that reduces the development of myopia among children. One of the rational is that light triggers the production of dopamine in the eye, and dopamine prevents the eye from growing excessively during childhood, and thus prevents form-deprivation myopia [2].

[1]: https://doi.org/10.1016/j.ebiom.2016.12.007

[2]: https://doi.org/10.1016/j.exer.2006.09.018