Factors Associated with Choroidal Thinning in Low Birthweight Infants

Abstract

Purpose : The choroid serves as the primary blood supply for photoreceptors, and its thinning has been hypothesized as a cause of poor visual outcomes in low birthweight (LBW) infants. Choroidal capillaries, similar to capillaries of the choroidal plexus of the brain, lack the protective filtration of the blood-brain-barrier and are susceptible to systemic insults. We examine the relationship between choroidal thinning and health metrics in LBW infants.

Methods : We measured choroidal thickness on investigational swept source optical coherence tomography (SS-OCT) of premature infants captured at 36 ± 1 weeks postmenstrual age as part of the IRB approved BabySTEPS (STudy of Eye imaging in Premature infantS). Preterm birth history and clinical health course was recorded as part of the study. One eye of each patient was randomly selected for analysis, and appropriate statistical tests were performed to assess differences in choroidal thicknesses between infants with vs without abnormal conditions present in 10 or more infants.

Results : Subfoveal choroidal thickness could be measured in 62 of 65 eyes (95%). Mean choroidal thickness was 232.8 ± 83.0 µm, with no significant difference between left and right eyes (225.4 ± 79.4 vs. 235.1 ± 82.2, respectively; p = 0.58). Conditions in infants having significantly thinner choroid included: pulmonary interstitial emphysema (n = 11, 162.4 ± 63.8 µm “with” vs. 250.1 ± 78.4 µm “without”, p = 0.002), receipt of indomethacin within 24 hours of life (n = 24, 191.4 ± 75.3 µm vs. 262.1 ± 76.0 µm, p < 0.001 ), and presence of blood in a cerebral ventricle (n = 10, 148.2 ± 48.3 µm vs. 235.7 ± 76.8 µm, p = 0.012). 24 infants had at least one of these health issues, and 14 of these had more than one. A thinner choroid was also significantly associated with lower weight at 36 weeks (r² = 0.40, p < 0.001).

Conclusions : Choroidal thinning at 36 weeks postmenstrual age is associated with several non-ocular medical conditions in preterm infants. The impact of these systemic conditions on the choroid and its vasculature may help explain why some preterm infants are more likely to have poor visual outcomes in the absence of primary ocular diseases.

This is a 2020 ARVO Annual Meeting abstract.

 

Fig 1: SS-OCT foveal B-scans of low birthweight infants: (a) otherwise healthy (subfoveal choroidal thickness, 363.6µm); (b) with pulmonary interstitial edema, early indomethacin treatment, and blood in a cerebral ventricle (subfoveal choroidal is thin, 77.9µm).