Cycloplegic refraction data were recorded originally in conventional form as sphere (S), plus cylinder (C), and axis (α). Using a custom spreadsheet (Excel; Microsoft, Inc., Redmond, WA, USA), they were converted into their power vector components: M (SEQ),
J0 (positive
J0 indicates with-the-rule [WTR] astigmatism, negative
J0 indicates against-the-rule [ATR] astigmatism), and
J45 (oblique astigmatism; positive
J45 indicates 135° astigmatism while negative
J45 indicates 45° astigmatism).
15 To calculate anisometropia, the absolute value of the SEQ interocular difference was calculated. In this study, significant anisometropia is defined as anisometropia ≥1 D. To delineate refractive development, SEQ, SEQ at the initial visit, and SEQ at the final visit were analyzed. Myopic shift was defined as the SEQ difference between the initial and final visits (
SEQinitial −
SEQfinal). Therefore, a positive myopic shift means decreased hyperopia. To evaluate longitudinal changes in refractive error, we analyzed our data according to age subgroups: 3, 6, 9, and 12 months, and 1.5, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, and 12 years.