Normative axial length growth references in preterm and term infants for clinical use in early onset glaucoma

To establish normative axial length growth references for preterm infants without retinopathy of prematurity (ROP) and term-born children under 5 years and construct templates to aid early-onset glaucoma evaluation and monitoring.

In this prospective cross-sectional study, preterm infants (<37 weeks' gestational age) without ROP and healthy term-born children under 5 years were included. Axial length was measured using ultrasonic biometry. Growth references were plotted on logarithmic scales: postmenstrual age (PMA) for preterm infants, months for term children. Analysis of covariance compared the growth slopes. Multiple linear regression assessed predictors of axial length growth (gestational age, measurement age and birth weight).

220 eyes (101 term, 119 preterm) were analysed. The mean gestational age was 39.5±0.84 weeks in term and 31.8±2.17 weeks in preterm infants. The mean axial length was 21.15±1.6 mm in term and 16.95±1.15 mm in preterm infants at 17.3±13.2 months and 43.5±5.9 weeks PMA, respectively. In preterm infants, PMA and birth weight showed a strong independent positive association with axial length. In term infants, only PMA showed a strongly independent positive association with axial length. Collinearity diagnostics indicated no evidence of significant multicollinearity in either group. Preterm eyes had a steeper slope compared with term eyes (0.16 vs 0.02).

The steeper axial elongation in preterm infants may represent compensatory postnatal growth and is clinically important for the assessment of glaucoma in the preterm period. The derived growth references offer practical clinical tools for distinguishing physiological ocular growth from pathological enlargement due to elevated intraocular pressure in neonatal-onset glaucoma.