Alterations in Retinal Layer Thickness and Reflectance at Different Stages of Diabetic Retinopathy by En Face Optical Coherence Tomography

Abstract

PurposeThis article reports a method for en face optical coherence tomography (OCT) imaging and quantitative assessment of alterations in both thickness and reflectance of individual retinal layers at different stages of diabetic retinopathy (DR).MethodsHigh-density OCT raster volume scans were acquired in 29 diabetic subjects divided into no DR (NDR) or non-proliferative DR (NPDR) groups and 22 control subjects (CNTL). A customized image segmentation method identified eight retinal layer interfaces and generated en face thickness maps and reflectance images for nerve fiber layer (NFL), ganglion cell and inner plexiform layers (GCLIPL), inner nuclear layer (INL), outer plexiform layer (OPL), outer nuclear layer (ONL), photoreceptor outer segment layer (OSL), and retinal pigment epithelium (RPE). Mean thickness and intensity values were calculated in nine macular subfields for each retinal layer.ResultsEn face thickness maps and reflectance images of retinal layers in CNTL subjects corresponded to normal retinal anatomy. Total retinal thickness correlated negatively with age in nasal subfields (R ≤−0.31; P ≤ 0.03, N = 51). In NDR subjects, NFL and OPL thickness were decreased (P = 0.05), and ONL thickness was increased (P = 0.04) compared to CNTL. In NPDR subjects, GCLIPL thickness was increased in perifoveal subfields (P < 0.05) and INL intensity was higher in all macular subfields (P = 0.04) compared to CNTL.ConclusionsDepth and spatially resolved retinal thickness and reflectance measurements are potential biomarkers for assessment and monitoring of DR.

Alterations of Retinal Pigment Epithelium–Photoreceptor Complex in Patients with Type 2 Diabetes Mellitus without Diabetic Retinopathy: A Cross-Sectional Study

“…Gella et al [9] and Verma et al [10] have found that photoreceptor (PR) layer thickness significantly decreased in diabetic subjects without DR com-pared to healthy controls, with the Copernicus OCT and a manual measurement method. However, Wanek et al [11] did not find significant difference in OS and RPE between subjects without DR and controls with the Spectralis OCT and a customized image segmentation method. Ferreira et al [12] have reported a thicker RPE and a thinner PR in diabetic patients without DR when compared with nondiabetic controls with the built-in automatic segmentation software of the Spectralis OCT and proposed that the retinal thickness did not have linear relationship with the duration of diabetes (patients with longest diabetes duration had thicker PR thickness than those of moderate duration).…”

“…They discovered the damages of the retinal nerve fiber layer (RNFL) and ganglion cellinner plexiform layer or ganglion cell layer (GCL) [6][7][8]. Some other studies [9][10][11][12] have focused on the outer layers of the retina, such as the outer nuclear layer (ONL), inner segment photoreceptors, or outer segment photoreceptors (OS). However, these studies have noted inconsistent results.…”

Ganglion cell layer thickening in well‐controlled patients with type 1 diabetes: an early sign for diabetic retinopathy?

“…The PR layer has been reported not to change in diabetes (Vujosevic & Midena 2013;Wanek et al 2016) and from a pathophysiological view, alterations in this layer are hardly a marker for early signs of DR or DME. In the one publication about thinning of the PR layer in patients with diabetes, PR thickness was only measured at one unstandardized point of interest and it is doubtful that the results reported are reproducible with less variance than the reported 7 lm difference between the groups (Verma et al 2009).…”

The Use of Optical Coherence Tomography for the Detection of Early Diabetic Retinopathy

“…The report by Toprak et al showed that the photoreceptor inner segment ellipsoid layer had significantly lower reflectivity (both relative and absolute) in eyes with mild NPDR compared to control eyes [50]. In the previously mentioned SD-OCT report of Wanek et al, the INL intensity was higher in all macular subfields of eyes with non-proliferative DR compared to healthy controls, while all other layers showed no significant difference [26].…”

“…In another study employing en-face OCT imaging, RNFL and OPL thickness decreased while ONL was thicker in subjects with no DR when compared to the corresponding measures in healthy controls. In eyes with non-proliferative DR, the GCL + IPL were thicker in the perifoveal subfields [26]. Gundogan et al described RNFL, ganglion cell complex (GCC), and total macular thickness in 90 T1DM subjects with no DR and compared them to 100 age-and sex-matched controls.…”