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

Abstract

Our landmark-based analysis of OCT images using reflectometry and manual segmentation provides complementary findings in comparisons of normal and immature foveal structures. We show a central thickness increase in the outer nuclear layer, outer plexiform layer, and postreceptor layers in preterms with signs of arrested foveal development. We found no indication of abnormal photoreceptor inner or outer segment development in preterms.

Structural consequences of arrested foveal development in preterms with persisting signs of immaturity

“…The major finding of the present follow-up study is that an immature fovea in preterms is associated with a marked retardation of centrifugal displacement of IRL and OPL compared with controls. Although our results cannot be generalised due to the low number of subjects, our model confirms the proposal of an arrested migration of inner retinal cells and cone pedicles in preterms with signs of foveal immaturity during foveal development [10,11,22]. The degree and extent of retardation in each group of preterms seems related to the severity of signs of immaturity characterising the group as shown by the marked difference in retardation among the three PG selected on the basis of degree of IRL persistence and FD.…”

“…A detailed description of the subjects and the imaging procedure is given elsewhere [11] but is outlined here.…”

“…Layer thickness was measured in straight scans, i.e. horizontal SD-OCT B-scans with entrance beam positions through the pupil centre with a distinct light reflex in the foveal pit, and tilt-up scans, obtained with OCT entrance beam positions displaced from the pupil centre, from preterms and controls as described in a previous study [11]. We obtained reflectivity profiles of the OPL and manual segmentation of the INL, the combined GCL and inner plexiform layer (IPL), and the combined Henle fibre layer (HFL) and outer nuclear layer (ONL).…”

“…The maturation continues postnatally and the disappearance of inner retinal layers (IRL) cells and cone pedicles is not complete until 17th months after term birth [4]. High resolution optical coherence tomography (OCT) studies have confirmed these maturation changes around birth [5,6] and also demonstrated persistent signs of immaturity in preterms both with and without retinopathy of prematurity (ROP) [7][8][9][10][11][12]. In general, these studies have found that the maturation and lengthening of inner segments (IS) and outer segments (OS) of the foveal photoreceptors is within normal range.…”

“…Characteristic persisting signs of immaturity in preterms are increased thickness of the different layers of the inner retina together with presence of a sheet of outer plexiform layer (OPL) covering FC in combination with a reduced foveal depression [11]. An increased IRL thickness associated with a decreased foveal depth (FD) is still observed at adult age in most preterms born before 28 weeks of gestation [10,13].…”