Statistical analysis
Before study initiation, we calculated the necessary sample size to ensure feasibility, we recruited 30 volunteers to observe the resolution limit of discernible change in spherical power. The mean resolution limit of change in spherical power was 0.05 ± 0.01. The test level was 0.05 and the test power was 0.80, 110 volunteers were needed based on the following sample size calculation formula. (SPSS 20.0 (IBM, Armonk NY) statistical software was used for analysis. Statistical significance was set at p ≤ 0.05. For continuous variables, data are presented as mean ± SD. Distributional normality was tested between different groups. The single-sample t-test was used to compare the theoretically derived resolution limit and the actual resolution, and the paired 