Comparison of Retinal and Choroidal OCT Measures and Features at Term Equivalent Age in Preterm and Term Infants

TL;DR

Preterm infants show retinal and choroidal differences compared to term infants at term-equivalent age, with thinner choroids linked to thicker inner retinas.

Contribution

This study identifies novel associations between preterm birth, ROP severity, and retinal/choroidal OCT features at term-equivalent age.

Findings

Preterm infants had thicker inner retinas and thinner choroids compared to term infants.

More severe ROP and thinner choroids were associated with increased inner retinal thickness.

Ellipsoid zone presence at the fovea was more common in term infants.

Abstract

To evaluate macular optical coherence tomography (OCT) features at term-equivalent age in preterm and term infants, and to test the hypothesis that both preterm birth and retinopathy of prematurity (ROP) are associated with differences in OCT measures and features at term-equivalent age, with the choroid potentially influencing the outer retina.

This study analyzed data for 162 preterm and 78 term infants from prospective, handheld OCT imaging studies, with images of both eyes at 37 to 42 weeks postmenstrual age (PMA). Quantitative and qualitative features, from reading center grading, were compared between preterm and term infants, with subgroup comparison between stage <2 vs. more severe ROP. Multivariate analyses explored the associations of OCT features with variables including gestational age (GA), ROP, and choroidal thickness, adjusting for PMA at imaging and intereye correlation using generalized estimating equations.

Compared to term infants, preterm infants had a greater total and inner retinal thickness at the fovea (232.4 [mean] ± 126.9 [SD] vs. 108.0 ± 35.3 µm and 47.3 ± 20.7 vs. 25.0 ± 14.8 µm, respectively; both P < 0.001), and thinner choroid (267.2 ± 90.3 vs. 350.2 ± 161.4 µm; P < 0.001). Rates of intraretinal fluid were higher (63.8 vs. 6.6%; P < 0.001) in preterm infants, whereas subretinal fluid was only present (7.0%) in term infants. Despite similar outer retinal thickness, the ellipsoid zone was more frequently observed at the foveal center in term infants (35.2%) than preterm infants (8.5%; P < 0.001). Multivariate analyses identified significant associations between higher GA and reduced foveal inner and outer retinal thicknesses. More severe ROP and decreased choroidal thickness were associated with increased foveal inner retinal thickness (both P < 0.01), but not with outer retinal thickness.

By term-equivalent age, foveal inner retinal immaturity and photoreceptor under-development is evident in preterm versus term-born retinas. A thinner choroid is associated with thicker inner retina.