Evaluating the association of clinical factors and optical coherence tomography retinal imaging with axial length and axial length growth among preterm infants

Purpose To study the association of clinical factors and optical coherence tomography (OCT) retinal imaging with axial length (AL) and AL growth in preterm infants Methods Among a subgroup of infants from the prospective BabySTEPS study who were screened for retinopathy of prematurity (ROP) and had both AL measured and OCT imaging performed, we analyzed data collected prior to 42 weeks postmenstrual age (PMA) and prior to ROP treatment. Using linear mixed effects models, we evaluated associations between AL and AL growth with gestational age (GA), birthweight, PMA, sex, race, multiparity, maximum ROP stage, and OCT features. Results We included 66 infants (132 eyes), mean GA = 27.6 weeks (SD = 2.3; range: 23.0–34.4) and mean birthweight = 961 g (SD = 269, range: 490–1580). In the final predictive model, longer AL was associated with earlier GA, higher birthweight, later PMA, non-White race, and thicker subfoveal choroid (all p values ≤ 0.01). AL increased linearly up to 42 weeks PMA. There was no difference in AL growth rate by GA, sex, race, multiparity, maximum ROP severity, central foveal thickness, or subfoveal choroidal thickness (all p values > 0.05); but AL growth rate was slower in infants with lower birthweight ( p = 0.01). Conclusions Among preterm infants, those with earlier GA, higher birthweight, later PMA, non-White race, and thicker subfoveal choroid had the longest AL. AL increased linearly up to 42 weeks PMA and lower birthweight was associated with slower AL growth. These findings may improve the accuracy of measurements taken on preterm infants using imaging techniques affected by AL (e.g., measuring lateral dimensions on OCT). Trial registration https://clinicaltrials.gov/ct2/show/NCT02887157 , date of registration: August 25, 2016