Normal range of ocular biometry in healthy children: A systemic review and meta-analysis of 33,559 individuals under seven years of age

Purpose: To conduct a systemic review and meta-analysis on the normative range of ocular biometry in healthy children under seven years of age. Methods: A literature search was performed using the PubMed (MEDLINE) database. The main outcomes were normative values of axial length (AL), central corneal thickness (CCT), cornea curvature (CC), anterior chamber depth (ACD), lens thickness (LT) and vitreous chamber depth (VCD). Pooled estimates were obtained with a random-effects meta-analysis. Multivariate meta-regressions ascertained the moderator-related trends. Results: We included 47 studies for a total of 33,559 subjects. The pooled ALs for 0.0–1.9 years, 2.0–3.9 years and 4.0–6.9 years were 18.33 mm (95% confidence interval [CI] 17.57–19.09), 21.71 mm (21.49–21.93) and 22.37 mm (22.29–22.45), respectively. Children aged 0.0–1.9 years had a greater CCT (576.70 μm, 567.20–586.21), steeper cornea (7.41 mm, 7.16–7.65) and shallower ACD (2.46 mm, 2.23–2.69). LT ranged from 3.65 to 3.74 mm for 0–6 years, and VCD increased from 11.94 mm at birth to 15.36 mm at 4.0–6.9 years. Differences in AL between East Asian and non-East Asian children were found below two years of age (17.30 mm vs. 18.40 mm, p = 0.008) and for CC at 4.0–6.9 years of age (7.82 mm vs. 7.79 mm, p = 0.004). In a multivariate meta-regression, AL, CC, ACD and VCD increased with age (p < 0.05 for all), while CCT decreased with age (p = 0.0007). Conclusions: This study reports normative data for ocular biometry in children. Few differences were found with ethnicity in the ocular biometry of infants and pre-schoolers.