Outer Retinal and Choroidal Changes in Adolescents with Long-Lasting Type 1 Diabetes

Abstract

This study aimed to assess outer retinal layer (ORL), retinal pigment epithelium (RPE), choroid (Ch) and choriocapillaris (CC) modifications in adolescents with long-lasting (>10 years) type 1 diabetes (T1D) without (noDR) or with diabetic retinopathy (DR). ORL and RPE thickness were measured at optical coherence tomography (OCT) macular scans. Vascular parameters of Ch and CC were quantified after elaboration of macular OCT-angiography (OCTA) images. Insulin dose and auxological and metabolic parameters were correlated with OCT and OCTA findings in patients. ORL thickness was higher in DR eyes than in noDR and healthy controls (HC), and RPE thickness was higher in noDR and DR eyes than in HC, with statistical significance for some sectors in noDR versus HC. No OCTA parameters of CC and Ch differed among groups, and no significant correlation was observed with auxological and metabolic parameters. In conclusion, ORL and RPE were both increased in adolescents with long-lasting T1D. Such changes were not associated with insulin dose and glycemia control, nor to any choroid or choriocapillaris flow change clinically detectable at OCTA, and they could be potential imaging biomarkers of disease progression.

Keywords: OCT; OCT angiography; adolescents; choriocapillaris; choroid; continuous glucose monitoring; diabetic retinopathy; outer retina; retinal pigment epithelium; type 1 diabetes.

Figure 1

OCT scans of a noDR patient with the automatic segmentation provided by Spectralis software: (a) outer retinal layers, ranging from the external limiting membrane (ELM) in rose to the Bruch membrane (BM) in red; (b) retinal pigment epithelium (RPE) delimited by the photoreceptors separation line in light blue and BM in red; (c) “Outer retinal layers slab minus RPE slab” (ORL), including ELM plus myoid zone, ellipsoid zone and outer segments of the photoreceptors.

Figure 2

OCTA en-face images of the choriocapillaris (A) and of the choroid (B) of a healthy subject as obtained from a 10° × 10° macular map centered onto the foveola. Elaboration of the same images by means of ImageJ software (version 1.53s, National Institutes of Health, Bethesda, MD, USA) for choriocapillaris (C), and for choroid (D).