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Susan E. Yanni, Jingyun Wang, Melody Chan, Joseph Carroll, Sina Farsiu, Joel N. Leffler, Eileen E. Birch; Foveal Avascular Zone and Foveal Pit Formation in Regressed ROP. Invest. Ophthalmol. Vis. Sci. 2011;52(14):3133.
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© ARVO (1962-2015); The Authors (2016-present)
Vascularization of the macula takes place between 24-27 weeks gestational age (GA). Preterm birth, and the resultant change in retinal pO2, may affect the developmental interactions among formation of a vascular plexus around the foveal avascular zone (FAZ), formation of the foveal depression, and displacement of inner retinal layers away from the incipient fovea. Previously, we showed that birth before 28 weeks GA resulted in a failure of the inner retinal neurons to migrate away from the fovea. Here we examined whether foveal vascular abnormalities accompany the inner retinal abnormality, and whether they are coincident.
SD-OCT volume scans were obtained from 11 children with regressed ROP (normal-appearing posterior poles; 23-27 wk GA; age range, 5-15 yrs) and 12 full-term controls (age range, 7-16 yrs). A custom-designed Matlab program was used to measure total retinal thickness and the thickness of individual retinal layers (Hood et al., IOVS, 2009). SD-OCT data were also fit using a mathematical model designed to capture the contour of the foveal surface, and metrics of foveal morphology were extracted (depth, diameter, slope). Summed voxel projections for the GCL-INL were used to identify the FAZ.
Despite similar foveal diameters (1857.1±66.4 NML vs 1705.1±234.9 um ROP), children with regressed ROP had significantly smaller FAZ diameters than controls (443.5±69.5 vs 818.0±236.1 um; p<0.001).The foveas of ROP children were significantly shallower (p<0.001) and total retinal thickness at the fovea was significantly increased (p<0.001) compared to controls. The GCL-IPL thickness was significantly (p<0.02) thicker in ROP children at the fovea through 400 um, but not at >800 um. FAZ diameter was negatively correlated with total foveal thickness (r2=0.40) and GCL-IPL thickness at the fovea (r2 = 0.61). No significant differences in IS or OS thickness, or ONL ratios were found between ROP children and controls.
Preterm birth results in abnormal foveal vascularization and a failure of the inner retinal neurons to migrate away from the fovea. Despite a small FAZ and shallow foveal pit, there were no detectable abnormalities in foveal cone packing or cone length. These findings suggest that the neurovascular interactions involved in foveal pit formation may not be linked to the centripetal forces that lead to cone packing.
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