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.