Associations between oxygen supplementation and choroid thickness in preterm infants

Abstract

Purpose : The choroid plays a crucial role in the health and function of the outer retinal layers, yet little is known about the impact of perinatal systemic health factors on its development. There is some evidence that suggest hyperoxia is associated with a thinner choroid in preterm infants. We hypothesize that higher oxygen support during the intensive care period is associated with a thinner subfoveal choroid in preterm infants.

Methods : Preterm infants were imaged using handheld swept-source optical coherence tomography (SS-OCT) as a part of the prospective, observational, IRB approved BabySTEPS (STudy of Eye imaging in Premature infantS) clinical study. Choroidal thickness (SFCT) was measured across the central 1mm at 36±1 weeks postmenstrual age (PMA) and averaged between eyes. Highest, mean, and lowest oxygen saturation (SpO2) and fraction of inspired oxygen (FiO2) values in a 24 hour interval on day of ROP screening at 31±1 and 36±1 weeks PMA were recorded and correlated with SFCT at 36±1 weeks PMA. For statistical analysis, FiO2 and SpO2 were categorized with low FiO2 binned as room air equivalent “FiO2=21%” or requiring extra support “FiO2>21%.”

Results : Mean (+/- standard deviation) SFCT was 199.4 ± 64.7 µm from 53 eyes (27 infants) at 36 weeks PMA. After univariable analysis, infants with higher FiO2 need (lowest value in 24 hours; FiO2=21% vs FiO2>21%) at 31 and 36 weeks PMA had a thinner choroid at 36 weeks (31 weeks: 205.9±12.5 vs 126.4±2.6 µm; 36 weeks:201.3±12.8 vs 162.2±3.7 µm, p=0.003 for all). SpO2 and other FiO2 measures at 31 and 36 weeks PMA were not associated with SFCT or could not be correlated due to limited sample size. Higher FiO2 need (lowest value) remained significant in the multivariable analysis at both 31 weeks and 36 weeks PMA (p=0.001 and p=0.002 respectively).

Conclusions : Preterm infants requiring higher levels of oxygen support, reflected by increased FiO2 needs at both 31 and 36 weeks PMA, had thinner subfoveal choroid measurements at 36 weeks. Understanding how higher FiO2 exposures effect the developing choroid and influence choroidal thickness measurements could help explain poorer visual outcomes in preterm infants with a thinner choroid. Further investigations are necessary.

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.

 

Figure 1: SS-OCT foveal B-scans at 36 weeks PMA from infant with lowest FiO2=21% (A) and lowest FiO2>21% (B).