Imaging the perifoveal retinal capillary vasculature of patients with diabetic retinopathy with Swept Source Optical Coherence Tomography Angiography (SS-OCTA)

Abstract

Purpose : SS-OCTA is a novel, non-invasive imaging technique that may be useful in the clinical management of retinal vascular disease. The aim of this observational study was to report SS-OCTA features of the perifoveal retinal capillary plexes of patients with diabetic retinopathy as well as to test potential applications of this technique in a clinical setting.

Methods : Twelve patients (twenty-two eyes) were enrolled. Inclusion criteria were the presence of diabetic retinopathy, with or without maculopathy. Exclusion criteria were: presence of significant media opacity or other concurrent retinal disease and history of previous endovitreal surgery. SS-OCTA was performed using the DRI OCT Triton Plus® (Topcon Corp., Tokyo, Japan). The imaged area was 3mm x 3mm, centered on the fovea. The SS-OCTA images of the superficial (SP) and deep (DP) perifoveal plexes were analysed quantitatively and qualitatively. Manual segmentation was performed for each scan.

Results : Our quantitative analysis showed that the mean Foveal Avascular Zone area in the SP was 0.466 ± 0.23 mm² and 0.519 ± 0.19 mm² in the DP. Image quality was graded as excellent (group A) 4/22 (18%), good (group B) 7/22 (31.8%), poor but gradable (group C) 9/22 (40.9%) and ungradable (group D) 2/22 (9.1%). The most common cause of poor image quality were motion artifacts, the most frequent being "white lines" (Fig.1) with associated "vessel displacement" (86,4%) followed by "projection artifacts" (27,3%) and "gap defects" (13%). SS-OCTA highlighted some of the features of diabetic maculopathy such as capillary drop-out (Fig.2), intraretinal microvascular abnormalities and cystoid cavities.

Conclusions : SS-OCTA is a promising imaging technique for the assessment of macular perfusion. This small pilot study demonstrated its potential use as an adjunct to traditional Fluorescein Angiography. The absence of dye allows visualisation of structures that would otherwise be masked by fluorescein leakage or staining. The primary drawback of SS-OCTA was the degradation of image quality due to motion artifacts. However, we observed that most images were of sufficient quality to allow for both qualitative and quantitative grading of diabetic maculopathy.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.

 

Fig.1 Example of multiple "white lines" and "vessel displacement" artifacts.

 

Fig.2 Example of areas of capillary drop-out in the superficial plexus.