Dear Editor,

Yamaguchi and colleagues [1] investigated peripheral optical quality and determined its relationship with axial elongation and myopic progression in children. On the basis that a “progressing group” of seven children had more initial hyperopic relative peripheral defocus than a “non-progressing” group of 22 children, despite both groups having similar initial central refractions and axial lengths, they concluded that progression of axial myopia in children is associated with hyperopic relative peripheral defocus.

I do not believe that the study supports this conclusion. While the central refraction difference between the two groups was not significantly different, this may be because of the small number in their progressing group; the initial mean refraction for the progressing group was about 1.4 D more myopic than that of the non-progressing group, and this is expected to give more hyperopic relative peripheral defocus [2–4]. The similar axial length between the groups means little without information about the gender distribution, because males have about 0.5 mm longer axial lengths than females of similar refractions and age [5–7]; also, again, there may have been insufficient children in this group to show a real difference.