We thank Drs Uzun and Pehlivan very much for their interest in our research. The questions they raised are important, and we are grateful for the opportunity to further complete our paper though the following reply.

Firstly, the effect of female participants’ menstrual cycle on choroidal thickness was very limited in our study. Among the 131 girls who participated in our study, 50 were over 10 years old, including only 1 13-year-old girl, 3 12-year-old girls, and 29 11-year-old girls. According to a recent study, the mean menses onset of urban Chinese girls is 12.27 years (95% CI: 12.16-12.39 years). Thus, the age distribution of female participants in our study limited the influence of menstrual cycle on choroidal thickness measurements.

Secondly, we must admit that the effect of children’s physical exercise status and consumption of caffeinated/decaffeinated food/beverages on choroidal thickness measurements were not particularly considered in our study. However, owing to the location and the design of the study, the variation of optical coherence tomography (OCT) measurements caused by these factors was very small.

As described in our paper, before the OCT measurement our participants underwent a serious of comprehensive ophthalmic examinations, including visual acuity, sensorimotor examination, slit-lamp biomicroscopy, tonometry, cycloplegic refraction, fundus examination, and measurement for axial length and corneal curvature. The cyclopegia alone would take 50 minutes, and finishing the whole process normally required at least 80 minutes. During this whole time, our participants had no dynamic physical exercise.

Caffeine is not considered healthy for children. The American Academy of Pediatrics recommends that adolescents get no more than 100 mg of caffeine a day, and younger children should not drink caffeinated beverages on a regular basis. Thus, Chinese parents do not give their children energy drinks, coffee, or tea for breakfast, and no caffeinated/decaffeinated food or beverage is allowed to be sold in schools. In our study, all of the SS-OCT images were acquired between 9 AM and 11 AM in the school, and children simply do not have the access to caffeine in such a school day morning.

We offer our thanks again for raising these questions about our study, and we hope our explanation is clear and reasonable.