Aim: The most common chorioretinal disease associated with preterm birth is retinopathy of prematurity (ROP). Retinopathy of prematurity and prematurity itself compromise normal macular development. The first aim of this study was to examine the vascular and structural chorioretinal changes in children born preterm with non-invasive imaging techniques such as optical coherence tomography (OCT) and optical coherence tomography angiography (OCTA). We investigated the association of macular changes with risk factors for the development of ROP. Additionally, we studied the structural-functional correlation of chorioretinal changes with 30 Hz flicker electroretinography (ERG) as a measure of cone function.
Hypothesis: Children born preterm have higher central macular vessel density, smaller foveal avascular zone (FAZ), higher central subfoveal retinal thickness (CSFT) and thinner subfoveal choroid thickness (SFCT). These OCT and OCTA parameters correlate with gestational age (GA) and birth weight (BW). The choroidal vascularity index (CVI) is decreased in children born preterm. CVI correlates with visual acuity and 30 Hz flicker ERG.
Methods: Prospective study of 41 children born preterm and 33 full-term age-matched children. Demographic data such as GA, BW, history of ROP, and risk factors for ROP development were collected. Imaging was performed using swept-source OCT and OCTA. The following parameters were studied: FAZ, foveal depth (FD), CSFT, SFCT, CVI and capillary density index (CDI) of the deep and superficial capillary plexus. Retinal function was assessed with best-corrected visual acuity and 30 Hz flicker ERG.
Results: Preterm children had significantly smaller FAZ, lower FD, and higher CSFT compared to full-term children; however, no differences were found in CDI between the groups. Macular changes correlated with numerous risk factors for ROP development. No significant differences in SFCT were detected between preterm and full-term children regardless of the presence of ROP. Preterm children with ROP had significantly reduced CVI compared to full-term children, but the CVI in the preterm children without ROP was not significantly affected. We found that lower CVI was correlated with a worse visual acuity. Preterm children had significantly longer 30 Hz flicker ERG latency and lower amplitude compared to controls; however, there was no change in 30 Hz flicker ERG parameters compared to controls if extreme preterm children were excluded. 30 Hz flicker ERG amplitude correlated with GA and some OCT parameters (FD and CSFT). No statistically significant correlation was found between CVI and 30 Hz flicker ERG.
Conclusions: Central macular changes were identified in preterm children. The study represents an original contribution to the knowledge about the influence of multiple risk factors for ROP development on macular morphological changes in preterm children. This study demonstrated no structural changes in the choroids of preterm children without ROP. Choroidal vascularity appears to be decreased in eyes with ROP, but the CVI was not influenced by prematurity itself. Preterm children show alterations in global retinal cone system function. The correlations between macular structural features and global retinal cone function revealed by flicker ERG may suggest a common underlying pathophysiological mechanism.
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