Microvascular parameters evaluated with optical coherence tomography-angiography in children: comparison between preterm and full-term patients

Insights into the developing fovea revealed by imaging

Early development of the fovea has been documented by histological studies over the past few decades. However, structural distortion due to sample processing and the paucity of high-quality post-mortem tissue has limited the effectiveness of this approach. With the continuous progress in high-resolution non-invasive imaging technology, most notably optical coherence tomography (OCT) and OCT angiography (OCT-A), in vivo visualization of the developing retina has become possible. Combining the information from histologic studies with this novel imaging information has provided a more complete and accurate picture of retinal development, and in particular the developing fovea. Advances in neonatal care have increased the survival rate of extremely premature infants. However, with enhanced survival there has been an attendant increase in retinal developmental complications. Several key abnormalities, including a thickening of the inner retina at the foveal center, a shallower foveal pit, a smaller foveal avascular zone, and delayed development of the photoreceptors have been described in preterm infants when compared to full-term infants. Notably these abnormalities, which are consistent with a partial arrest of foveal development, appear to persist into later childhood and adulthood in these eyes of individuals born prematurely. Understanding normal foveal development is vital to interpreting these pathologic findings associated with prematurity. In this review, we first discuss the various advanced imaging technologies that have been adapted for imaging the infant eye. We then review the key events and steps in the development of the normal structure of the fovea and contrast structural features in normal and preterm retina from infancy to childhood. Finally, we discuss the development of the perifoveal retinal microvasculature and highlight future opportunities to expand our understanding of the developing fovea.

Optical Coherence Tomography Angiography in Prematurity

Purpose: During normal foveal development there is a close interaction between the neurosensory and vascular elements of the fovea making it vulnerable to prematurity and retinopathy of prematurity (ROP). We aim to assess this potential effect on foveal development in preterms evaluated simultaneously with both optical coherence tomography (OCT) and OCT angiography (OCTA).Method: Unrestricted literature search in the PubMed and Cochrane library databases yielded 20 distinct citations. Fifteen were relevant and reviewed.Results: In preterms, OCTA demonstrated a significant decrease in the foveal avascular zone area and an increase in foveal vessel density. OCT showed a decrease in foveal pit depth and an increase in the thickness of the subfoveal retinal layers. Some studies correlated these changes with reduced vision.Conclusion: Changes in the vascular and neurosensory retina were found in premature children. It remains unclear whether this is related to prematurity alone or ROP and its treatment.