Importance of Considering the Middle Capillary Plexus on OCT Angiography in Diabetic Retinopathy

Abstract

PurposeTo quantify microvasculature changes in the superficial (SCP), middle (MCP), and deep capillary plexuses (DCP) in diabetic retinopathy (DR).MethodsRetrospective cross-sectional study at a tertiary academic referral center, in which 26 controls (44 eyes), 27 diabetic subjects without retinopathy (44 eyes), 32 subjects with nonproliferative retinopathy (52 eyes), and 27 subjects with proliferative retinopathy (40 eyes) were imaged with optical coherence tomography angiography (OCTA). Outcome measures included parafoveal vessel density (VD), percentage area of nonperfusion (PAN), and adjusted flow index (AFI) at the different plexuses.ResultsMCP VD and MCP AFI decreased with worsening DR, while PAN increased, mirroring changes within the DCP. The fitted regression line for MCP and DCP AFI were significantly different than the SCP, while DCP PAN differed from SCP PAN with disease progression. Higher SCP AFI and PAN were different in eyes with diabetes without retinopathy compared with controls. Unexpectedly, sex was found to independently influence MCP VD and AFI with worsening disease.ConclusionsOCTA parameters in the MCP and DCP displayed parallel changes with DR progression, different from the SCP, emphasizing the importance of physiologic considerations in the retinal capillaries. Thus, segmentation protocols that include the MCP within the SCP may be confounded. A difference in DCP PAN with worsening DR was unmasked relative to a prior study that included the MCP with SCP. We confirm that SCP AFI and PAN may serve as early indicators of microvascular changes in DR and identify an interaction between sex and the MCP deserving further study.

Microvascular Changes in the Choriocapillaris of Diabetic Patients Without Retinopathy Investigated by Swept-Source OCT Angiography

“…Moreover, recent studies also showed that additional segmentation and evaluation of the intermediate retinal layer from the superficial and deep retinal layers may enhance the ability of OCTA to detect early microvascular changes in diabetic eyes. 29,32,33 In this study, VAD and VSD were measured on the SRL, IRL, and DRL using our validated semiautomated segmentation algorithm. Our study showed that no significant difference was found in VSD or VAD in diabetic eyes without retinopathy compared to controls within the three vascular plexuses for a 6 × 6-mm scanning protocol.…”

Evaluation of different Swept’Source optical coherence tomography angiography (SS‐OCTA) slabs for the detection of features of diabetic retinopathy

“…), and the MCP seems to be of special interest (Onishi et al. ). The proprietary segmentation of the SS‐OCTA device used in this study did not allow to segment the MCP separately.…”

“…; Onishi et al. ), which is currently not available for the 12 × 12 mm area mainly due to the challenge of a lower resolution. However, quantification of a larger area is possible.…”

Future clinical applicability of optical coherence tomography angiography

“…This is important because histopathology indicates that this is an early site of damage in diabetic retinopathy . Indeed, several studies have concurred on this . However, the degree to which these vascular changes are related to visual acuity levels or to the risk of visual loss remains unknown.…”