Four-year change in ocular biometric components and refraction in schoolchildren: A cohort study

PURPOSE: To determine 4-year changes of ocular biometric and dioptric components in Iranian children aged 7–11 years following the first phase. METHODS: 468 children were evaluated in the first phase of the study in 2012 and again in 2016–2017. Multi-stage stratified cluster sampling was applied to select the participants. The Topcon autorefractometer and the LENSTAR/BioGraph biometer (WaveLight AG, Erlangen, Germany) were used for cycloplegic refraction and biometry, respectively. All measurements were repeated at 4 years as the baseline assessments. RESULTS: Of 468 children, 251 (53.6%) were boys. Spherical equivalent (SE) showed a marked myopic shift (P = 0.000) in the second phase which was significantly higher in boys (0.24 vs. 0.18 D) (P < 0.001). Axial length (AL) and anterior chamber depth (ACD) increased by 0.49 ± 0.05 and 0.12 ± 0.02 mm, while lens thickness (LT) and lens power (LP) decreased by 0.08 ± 0.01 mm and 1.59 ± 0.12 D, respectively (P < 0.05). The mean corneal curvature and thickness did not change significantly during 4 years. All biometric component changes were greater in boys. Biometric changes in different age groups showed a decreased LP, increased AL, and increased ACD in most age groups (P < 0.05), while LT and SE did not change significantly in the age groups 9 and 11 years and 8 and 9 years, respectively. Changes in the corneal thickness, diameter, curvature, and refractive astigmatism were not significant in any of the age groups (P > 0.05). CONCLUSIONS: Statistical and clinical changes were seen in AL, ACD, LP, and LT. The changes observed in biometric components (AL, ACD, and LT) had a sinus rhythm.