A time‐line model of developmental events within the human fovea based on imaging and histology data

Abstract

Purpose To create a time‐line model of developmental events during normal maturation of the inner and outer foveal layers based on imaging and histological studies. Methods Data from recently published imaging studies using hand‐held OCT during the period following premature birth (Dubis et al. 2012; Maldonado et al., 2012; Vajkovic et al., 2012) and histology of normal donor eyes (Dubis et al., 2012; Hendrickson et al. 2012; Vajkovic et al., 2012) was used to establish the timing of foveal developmental events from the time of mid‐gestation to early childhood. A model of the onset and maturation of the following foveal developmental events was constructed: Pit formation, extrusion of inner retinal layers, widening of the outer nuclear layer, separation of the hyperreflective inner segment layer from the RPE, and lengthening of the outer segment. Developmental events were graded as incipient, intermediate or mature. Results The normal developmental events within the central fovea are depicted along a logarithmic time‐line. The developmental models based on OCT or histology of the inner and outer retina show a close correspondence. The structural elements of the inner retina all reach near full to full maturity at term birth. At this time the outer retinal structures are immature and the maturation of the photoreceptor layers starts at an age of some postnatal weeks and reach near full to full maturity at one to three years of age. Conclusion The inner and outer foveal layers reach maturity within different time frames; the inner layers during the late part of gestation, and the outer layers during the first postnatal years. Our model is of importance when evaluating abnormalities in e.g. prematurity or albinism.

A methodological approach for evaluation of foveal immaturity after extremely preterm birth

“…Altogether, there seems to be independence between cone specialization and foveal pit formation as well as between ISe length and visual acuity . This supports a model in which the inner and outer part of fovea develops at different time frames, the inner part during late gestation and the outer part during the first postnatal years …”

“…Sjöstrand & Popovic recently presented a time‐line model of developmental events within the human fovea. By merging data based on OCT imaging and histological samples they presented a model showing how the inner and outer part of the fovea matures within different time frames, the inner retina during the late part of gestation and the outer retina during the first postnatal years.…”

Arrested Foveal Development in Preterm Eyes: Thickening of the Outer Nuclear Layer and Structural Redistribution Within the Fovea

“…21 Analyses of spectral-domain OCT (SD-OCT) images of the fovea before and after full-term birth have shown the dynamic changes in different foveal layers from approximately 30 weeks of gestation through different stages of normal maturation. 21,22 In general, development follows a timeline with continuous increases in layer thicknesses, 23 but in some preterms with or without retinopathy the development of the inner retina is arrested at a certain stage. 24,25 In a previous study of preterms born extremely premature we found persisting signs of immaturity indicating retardation of several developmental events when imaged by lowresolution SD-OCT at an age of 6.5 years.…”