Superficial capillary perfusion on optical coherence tomography angiography differentiates moderate and severe nonproliferative diabetic retinopathy.

Janice X Ong,Changyow C Kwan,Amani A Fawzi,Maria V Cicinelli,Demetrios G Vavvas

doi:10.1371/journal.pone.0240064

Janice X Ong, Changyow C Kwan + Show 3 more

Open Access

https://doi.org/10.1371/journal.pone.0240064

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Journal: PloS one	Publication Date: Oct 22, 2020
Citations: 28	License type: CC BY 4.0

Affiliation: Northwestern University

Abstract

PurposeTo identify objective optical coherence tomography angiography (OCTA) parameters that characterize the spectrum of non-proliferative diabetic retinopathy (NPDR), especially those that distinguish moderate from severe NPDR.MethodsSixty eyes of 60 patients with treatment-naïve NPDR (mild: 21, moderate: 21, severe: 18), 23 eyes with diabetes and no retinopathy, and 24 healthy control eyes were enrolled. OCTA slabs were segmented into superficial (SCP), middle (MCP), and deep capillary plexus (DCP) and thresholded by a new method based on DCP skeletonized vessel length. The foveal avascular zone (FAZ) area, parafoveal vessel density (VD), and adjusted flow index (AFI) from all three capillary layers and the vessel length density (VLD) of the SCP were compared between each severity group, after adjusting for age and image quality.ResultsAll vessel density markers decreased with increasing severity of NPDR. SCP VD and VLD demonstrated significant differences between eyes with diabetes with no retinopathy and mild NPDR (p = 0.001 and p < 0.001, respectively), as well as between moderate vs. severe NPDR (p = 0.004 and p = 0.009, respectively). MCP VD significantly decreased between moderate and severe NPDR (p = 0.01). AFI significantly increased in the SCP and showed a decreasing trend in the MCP and DCP with increasing NPDR severity.ConclusionsChanges in the SCP VD, SCP VLD, and MCP VD can distinguish severe NPDR from lower-risk stages. SCP changes may be more reliable due to their lower susceptibility to noise and projection artifacts. Thresholding OCTA images based on DCP skeletonized vessel length showed less variability in moderate and severe NPDR. Additional studies are warranted to validate this new thresholding method.

Highlights

Diabetic retinopathy (DR) results from long-term effects of hyperglycemia on the microvasculature of the eye
All vessel density markers decreased with increasing severity of non-proliferative DR (NPDR)
adjusted flow index (AFI) significantly increased in the SCP and showed a decreasing trend in the MCP and deep capillary plexus (DCP) with increasing NPDR severity

Summary

Introduction

Diabetic retinopathy (DR) results from long-term effects of hyperglycemia on the microvasculature of the eye. DR affects one-third of the over 460 million diabetic patients worldwide and is one of the leading causes of vision loss in patients aged 20–74 [1, 2]. Potential complications of PDR include vitreous hemorrhage, traction retinal detachment, and neovascular glaucoma, leading to irreversible vision loss [5]. NPDR is further subclassified as mild, moderate, or severe based on clinical features like microaneurysms, hemorrhages, exudates and vascular abnormalities [6]. While the one-year risk of progression to PDR is relatively low for patients with mild or moderate NPDR (5 and 15%, respectively), it is much higher in patients with severe and very severe NPDR, at 52% and 72%, respectively [7]. Despite the importance of NPDR staging for risk stratification and surveillance planning, current grading criteria are subjective, based on qualitative features, and are susceptible to clinician judgment and individual clinical presentation of the patient [8]

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