Correlation analysis of angles and with the refraction and anterior segment parameters in children

Aim To investigate the correlation of angles alpha and kappa with the refractive and biological parameters in children. MethodsThis case-series study included 438 eyes of 219 children (males/females = 105/114, age: 3-15 years). Ocular biometric parameters, including axial length, corneal radius of curvature (CR), white-to-white distance (WTW ), angle kappa and angle alpha, were measured using IOL Master 700; auto-refraction were assessed under cycloplegia. The eyes were assigned to different groups based on CR, WTW, and gender to compare the angles alpha and kappa, and analyze the correla-tions between the differences of biological parameters on angles alpha and kappa. ResultsThe means of axial length, CR, WTW, angle alpha, and angle kappa were 23.24 +/- 1.14 mm, 7.79 +/- 0.27 mm, 11.68 +/- 0.41 mm, 0.45 +/- 0.25 mm, and 0.27 +/- 0.22 mm, respectively. Angle alpha was correlated with CR and WTW (fixed effect coefficient [FEC] = 0.237, p = 0.015; FEC = -0.109, p = 0.003; respectively), and angle kappa also correlated with CR and WTW (FEC = 0.271, p = 0.003; FEC = -0.147, p < 0.001, respectively). Comparing subgroups, the large CR and small WTW group had larger angles alpha (0.49 +/- 0.27 vs. 0.41 +/- 0.21, p < 0.001; 0.46 +/- 0.27 vs. 0.44 +/- 0.21, p < 0.05, respectively) and kappa (0.29 +/- 0.25 vs. 0.24 +/- 0.15, p < 0.01; 0.29 +/- 0.25 vs. 0.26 +/- 0.19, p < 0.05, respectively). The differences in interocular angles alpha and kappa showed correlation with interocular WTW (r = - 0.255, p < 0.001; r = - 0.385, p < 0.001). Eyes with smaller WTW tended to have larger angle kappa (0.28 +/- 0.27 vs. 0.25 +/- 0.15, p < 0.05). ConclusionThe size of angle alpha/kappa may be correlated to CR and WTW, and a larger WTW eye may suggest a smaller angle kappa compared with the fellow eye.