FEB 17, 2012
The authors used spectral domain-optical coherence tomography (SD-OCT) to determine the dynamic morphologic development of the human fovea in vivo, comparing findings in prematurely born neonates with children and adults without ocular pathology. The results show that human foveal development continues after premature birth. The authors also established a human foveal development timeline to allow identification of unexpected retinal abnormalities that may provide new information about disease activity and a method for mapping foveal structures from infancy to adulthood.
A surprising finding was the presence of cystoid macular edema in 58 percent of premature neonates that appeared to affect inner foveal maturation. The authors say this could be an ocular biomarker linked to additional systemic or ocular disease activities but may have little impact on foveal development.
The study included 31 prematurely-born neonates, with nine children and nine adults serving as controls. After examination for retinopathy of prematurity, SD-OCT imaging was performed at the bedside in nonsedated infants 31 to 41 weeks postmenstrual age and at outpatient follow-up ophthalmic examinations. Semiautomatic retinal layer segmentation was performed, and central foveal thickness, foveal to parafoveal (FP) ratio (central foveal thickness divided by thickness 1000 µm from the foveal center) and three-dimensional thickness maps were analyzed.
The neonatal foveas showed several signs of immaturity: a shallow foveal pit, persistence of inner retinal layers (IRLs) and a thin photoreceptor layer (PRL) that was thinnest at the foveal center. Three-dimensional mapping showed displacement of retinal layers out of the foveal center as the fovea matured and the progressive formation of the inner/outer segment band in the opposite direction. The FP-IRL ratios decreased as IRL migrated before term and minimally after that, whereas FP-PRL ratios increased as PRL subcellular elements formed closer to term and into childhood.
However, timing of the development of the PRL in premature infants was not always linked to the timing of development of IRL. Therefore, some infants demonstrated highly developed IRL with delayed maturation of the PRL, and others demonstrated the opposite.
The authors say this study provides the first view into the development of living cellular layers of the human retina and of subcellular specialization at the fovea in premature infant eyes using portable SD-OCT. They conclude that their findings demonstrate that migration, redistribution and growth of subcellular structures occur in premature infants ex utero.