A thinner choroid has been hypothesized to result in poorer visual outcomes in infants with low birth weight. Researchers investigated this hypothesis in a prospective, observational trial called the Study of Eye Imaging in Preterm infantS (BabySTEPS) and found that choroidal development in preterm infants may be related to growth rate in the first few weeks after birth and prolonged use of supplemental oxygen.

The study enrolled infants who had been recommended for retinopathy of prematurity (ROP) screening, according to the American Association of Pediatrics guidelines. The researchers imaged the infants with an investigational hand-held OCT device at approximately 36 weeks postmenstrual age (PMA). They also analyzed material and infant clinical health data.

The researchers were able to measure subfoveal choroidal thickness in 82 of 85 infants (159 of 170 eyes). The mean thickness was 233µm.

They noted that a thinner choroid was significantly associated with a number of factors, including decreased growth velocity, lower birth weight, smaller head circumference, more days on oxygen support and being on oxygen support at the time of imaging. Other factors included younger age and presence of pulmonary interstitial emphysema and bronchopulmonary dysplasia (BPD).

“Many preterm infants require oxygen supplementation, and there is debate among neonatologists regarding how to find the ideal oxygen saturation target for each neonate that both avoids hypoxia and hyperoxia,” the researchers noted in their paper. “The effects of hyperoxia on vasculature development have been well-studied in the context of BPD and ROP. Hyperoxia induces oxidative stress and the formation of reactive oxygen species, impairing vascular development and resulting in reduced density of the pulmonary vascular bed in BPD and arrest and pruning of the retinal vasculature in ROP.”

They also noted that hyperoxia at this early developmental stage causes VEGF downregulation, which is key for angiogenesis.

“We postulate that increased oxidative stress and downregulation of VEGF may also be arresting the vascular development of the choroid, resulting in a thinner choroid in these infants, the researchers wrote. They concluded that “a thinner choroid at 36 weeks in preterm infants is independently associated with slower postnatal growth velocity and the use of supplemental oxygen.”

Michalak SM, Mangalesh S, Shen LL, et al. Systemic factors associated with a thinner choroid in preterm infants. Ophthalmology Science 2021. [Epub June 6, 2021].