Analysis of the Choroid and Its Relationship with the Outer Retina in Patients with Diabetes Mellitus Using Binarization Techniques Based on Spectral-Domain Optical Coherence Tomography

Abstract

(1) Background: We aimed to reveal the relationship between the choroid and the outer retina with optical coherence tomography (OCT) in patients with diabetes mellitus (DM) with mild or no diabetic retinopathy (DR) in order to find early biomarkers for progressing retinopathy. (2) Methods: We performed a prospective study including 61 eyes of patients with type 1 or type 2 DM and 36 eyes of healthy controls. All subjects were imaged with Spectralis OCT. The choroid was assesseed using enhanced depth imaging OCT (EDI-OCT). Binarization of subfoveal choroidal images was done with public domain software, ImageJ (version 1.53a; National Institutes of Health, Bethesda, Maryland, USA). (3) Results: Luminal area, stromal area and total choroidal area were significantly decreased in diabetic patients compared to control: 0.23 ± 0.07 vs. 0.28 ± 0.08, p = 0.012; 0.08 ± 0.03 vs. 0.10 ± 0.04, p = 0.026; 0.31 ± 0.09 vs. 0.38 ± 0.11, p = 0.008. The thickness of retinal pigment epithelium (RPE) correlated positively with the choroidal vascularity index (CVI). The correlations between outer nuclear layer (ONL), photoreceptors (PR) and foveal choroidal thickness (FChT) were moderately negative. (4) Conclusion: Thicker RPE and a thinner PR layer may be assigned the role of early biomarkers signaling the conversion time to progressing retinopathy.

Correlation between Choroidal Vascularity Index and Outer Retina in Patients with Diabetic Retinopathy

“…Our findings are partly in agreement with the results published by Wang et al, according to whom DR patients presented with significantly lower choroidal, ORL, and RPE thickness than the controls, without significant differences observed between patients with concomitant DME and without [17]. Damian et al found thinner ONL and ORL in patients in whom diabetes coexisted with mild DR or lack thereof, without concomitant DME [54]. Other authors reported outer retinal atrophic changes in DME [13] with PROS (photoreceptor outer segment) shortening [13,44].…”

“…Consistently with previous reports [54,55], we found no significant correlations between choroidal parameters (CVI and choroidal thickness) and outer retinal parameters in healthy controls.…”

“…Damian et al analyzed correlations between choroidal and outer retinal parameters in diabetic patients with mild DR or lack thereof, without concomitant DME. They found significant correlations between CVI and RPE thickness as well as between choroidal thickness and photoreceptor layer thickness [54]. While the results of that study could be partially consistent with our findings in the DR + DME− group, the analyzed cohort differed considerably, as it included patients with mild or absent DR.…”

Local Inflammatory Biomarkers and Potential Inflammation-Targeting Therapies in Diabetic Retinopathy

“…Damian and al. found decreased RPE thickness in almost all quadrants in the PDR-DMO group as opposed to NPDR-DMO group, where the quadrants number was lower [86]. This finding was explained by a disruption of the RPEphotoreceptors complex due to ischemia and level of inflammation that varies according to the stage of DR. Cysts larger than >200 μm in the outer nuclear layer (ONL) are seen in advanced stages of DME and may cause irreversible damage to visual functions.…”

Choroidal Assessment in Patients with Type 2 Diabetes Mellitus and Non-Proliferative Diabetic Retinopathy by Swept-Source Ocular Coherence Tomography and Image Binarization

“…Tan et al found no differences in TCA, LA, and SA in patients without DM versus patients with DM with or without DR [ 23 ]. Conversely, Damian et al reported a significant difference between normal subjects and pooled DM and DM with mild NPDR subjects regarding TCA, LA, and SA, but no differences when they evaluated the DM versus DM with mild NPDR subjects [ 54 ].…”