The Relationship Between Anthropometric Z-Score Measurements and Ocular Structures in Turkish Children

**Background:** Previous studies have shown that anthropometric measurements such as height and weight are associated with ocular dimensions, including axial length (AL), anterior chamber depth (ACD), corneal curvature, and refractive error. However, the use of Z-scores—standardized measures of deviation from the population mean—has not been applied to this relationship. This study aimed to investigate the association between height-for-age Z-score (HFAsZ) and BMI-for-age Z-score (BMIsZ) with ocular biometric parameters in healthy Turkish children, and to identify clinically relevant Z-score cut-offs.

**Methods:** This prospective observational case series included 725 eyes of 725 healthy children (392 females, 333 males) aged 36-178 months (mean 101.6±30.8 months) who presented for routine ophthalmological examination between November 2019 and March 2023. Exclusion criteria included age >15 years, systemic disease affecting growth, regular medication, ocular disease other than refractive disorders, and inability to perform measurements. Height and weight were measured using a digital scale and wall-mounted stadiometer; BMI was calculated as kg/m². Z-scores were computed using WHO Anthro (for children <60 months) and WHO AnthroPlus (for children ≥60 months) software. Ocular parameters—spherical equivalent refraction (SER), AL, ACD, average corneal radius (CR), average corneal power (CP), and central corneal thickness (CCT)—were measured under cyclopentolate hydrochloride 1% using auto-refractometer and biometry devices. Patients were grouped into low (L), normal (N), and high (H) Z-score categories based on cut-off values of ±1, ±1.5, ±2, and a final cut-off of -1 to +1.5. Statistical analysis used independent t-test, one-way ANOVA, and Pearson correlation; significance set at p<0.05.

**Key Results:** Mean HFAsZ was 0.1±1.9 (range -4.1 to 3.1) and mean BMIsZ was 0.7±1.3 (range -6.0 to 4.7). No significant sex differences were found for age, HFAsZ, or BMIsZ. Males had significantly longer AL (23.32±1.13 vs 22.76±1.29 mm, p<0.001), deeper ACD (3.83±0.27 vs 3.72±0.22 mm, p<0.001), larger CR (7.82±0.23 vs 7.71±0.26 mm, p<0.001), lower CP (43.19±1.29 vs 43.86±1.41 D, p<0.001), and higher CCT (571.23±35.6 vs 565.00±35.2 μm, p=0.039). For HFAsZ using the final cut-off (-1 to +1.5), significant differences were observed across L, N, and H groups for AL (L: 22.69±1.26, N: 23.01±1.23, H: 23.56±1.25 mm; H vs L p<0.001, H vs N p=0.002), ACD (L: 3.73±0.24, N: 3.77±0.25, H: 3.84±0.26 mm; H vs L p=0.019, H vs N p=0.049), CR (L: 7.67±0.23, N: 7.77±0.26, H: 7.84±0.22 mm; all pairwise p<0.01), and CP (L: 44.00±1.36, N: 43.52±1.40, H: 43.06±1.24 D; all pairwise p<0.03). No significant differences were found for SER or CCT. For BMIsZ, no significant differences were observed for any ocular parameter across any grouping. Height and weight were strongly correlated (r=0.856, p<0.001).

**Clinical Implications:** This study demonstrates that height-for-age Z-score, but not BMI-for-age Z-score, is significantly associated with ocular biometric parameters in children. Specifically, children with higher HFAsZ tend to have longer axial lengths, deeper anterior chambers, flatter corneas, and lower corneal power. The authors propose using HFAsZ cut-offs of -1 and +1.5 as clinically relevant thresholds for predicting ocular structural changes. These findings may help clinicians anticipate refractive and biometric changes in children based on growth patterns, potentially aiding in early identification of children at risk for myopia or other ocular conditions. The lack of association with BMIsZ suggests that height, rather than weight or adiposity, is the primary anthropometric driver of ocular development in this population. Limitations include a moderately small sample size and the single-center design. Future studies with larger, diverse populations are needed to validate these cut-offs and explore longitudinal relationships.