Abstract
Purpose: :
To anatomically correlate in-vivo morphological development of the human fovea from spectral domain optical coherence tomography (SDOCT) images to human histological specimens.
Methods: :
Portable, hand-held SDOCT images from 20 prematurely-born neonates, 27 term-newborns and 6 infants from an IRB approved study were compared to light micrographs of donor postmortem human eyes at 26-34 gestational weeks, 36-40 gestational weeks and 2-36 months of age. The donor eyes were obtained with the aid of the University of Washington Lion’s Eye Bank. Main outcomes measures were histological correlations of the hyperreflective and hyporeflective bands in fetal and infant SDOCT images, based on cellular changes in foveal morphology.
Results: :
SDOCT imaging in premature neonates correlates well with histological findings of a shallow foveal pit, persistence of inner retinal layers and a thin single layer of photoreceptors in the fovea. In term newborns, the fovea appears more mature with OCT images and histology illustrating deepening and widening of the foveal pit, thinning of inner retinal layers, but the persistence of a thin foveal photoreceptor layer. After birth a new outer hyperreflective SDOCT band appears which correlates to elongating inner and outer segments (IS/OS) distal to the external limiting membrane (ELM). This hypereflective band appears first peripheral to the fovea; histology images verify that foveal cones are the last to begin IS/OS elongation. At 24 months of age, SDOCT demonstrates a wider and flatter foveal pit with an absence of inner retinal layers, and prominence of the ELM/IS/OS hyperreflective SDOCT band. Histologically, there are only scattered inner neurons seen in the pit, while cones are stacked 4-6 deep in the foveal center and have IS/OS which now are as long as peripheral photoreceptors. The typical hyperreflective and hyporeflective SDOCT bands seen in adults can also be identified at this age.
Conclusions: :
We document normal pre- and postnatal development of the human fovea, and provide an anatomic correlation with the SDOCT signal. This correlation will be required for the clinical assessment of retinal pathology as SDOCT becomes an established diagnostic tool for neonates and infants.
Keywords: retinal development • microscopy: light/fluorescence/immunohistochemistry • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)