Study details marked changes in central retina after midgestation

This analysis of postmortem tissue from eyes ranging from midgestation to young adult found pronounced changes in human foveal morphology in both the inner and outer layers of the retina. In particular, the authors found a marked change in foveal photoreceptors from a single layer of short undeveloped cones up until birth to tightly packed and highly elongated cones in the young adult. They conclude that understanding these changes is essential to correctly interpretating neonatal SD-OCT images.

This paper expands the existing literature and shows that the human fovea develops over a very long period. Morphologically, the incipient fovea can be identified at 11 to 12 fetal weeks by its characteristic lamination. In the last half of gestation, the pit forms by ganglion cell layer, inner plexiform layer, and inner nuclear layer displacement, which is finished by 1 to 2 years of age.

Foveal cones change little in late gestation, but in the first year after birth they become elongated cells with long inner segment, outer segment, and axons, and by 4 to 6 years of age they develop the longest inner segment and outer segment in the retina. Concurrently, cone density increases by a factor of 10. These processes are completed before 10 years, when the fovea has its adult characteristics.

The authors write that with technical advances in SD-OCT imaging making it possible to study prenatal and neonatal human eyes, the data presented here will be critical in interpreting clinical images of retinal microstructures in young infants and will provide a reference of normal development that will aid in the diagnosis of abnormal development detected in SD-OCT.