Abstract
Purpose :
To evaluate early choriocapillaris (CC) microvascular changes in the macula in patients with diabetes mellitus (DM) without and with initial signs of diabetic retinopathy (DR), using Swept-Source Optical Coherence Tomography Angiography (OCT-A).
Methods :
144 eyes of 144 consecutive subjects (48 healthy controls, 48 patients with DM without DR (noDR) and 48 patients with mild DR (DR)) were prospectively evaluated. All subjects underwent a complete eye examination and OCT-A (DRI OCT Triton plus Topcon Medical Systems Europe, Milano, Italy) in a standardized fashion with 3mm X 3mm scan centered on the macula. Central choroidal (CCT) and macular thickness were also recorded by OCT using a 6mm radial scan centered on the macula. Exclusion criteria were: any ocular or systemic disease other than DM, presents of macular edema and any previous eye surgery. OCT-A slab of CC plexus was analyzed with ImageJ (version 1.51, provided in the public domain by the U.S. NIH). Images were thresholded and binarized and an Analyse Particle analysis (AP) (ImageJ plugin) was performed to quantify the number and the total and average area (TA, AA) of flow voids (area without signals). Statistical analysis was performed with one-way analysis of variance corrected for covariates (ANCOVA) including age, followed by post hoc Sheffè test for pairwise comparisons among the three groups. The correlation among non-normally distributed variables were assessed using the Spearman’s rank test.
Results :
Mean age was 59.9±13.4 in controls, 65.1±10.9 in noDR and 67.4±13.2 in DR group (p=0.013); There was no significant difference in visual acuity among the three groups, neither in HbA1c and DM duration between noDR and DR groups. Flow voids number showed a statistically significant decrease from control, to noDR and to DR (p=0.005). TA and AA progressively increase from controls to noDR and DR group reaching statistical significance in DR (p<0.001). CCT progressively decreased from controls to no DR and DR group (p<0.001). All parameters of AP were significantly correlated to CCT thickness in all three groups (p<0.05).
Conclusions :
Alterations of CC perfusion were already detected in the early stages of DR and also in patients without signs of DR. OCT-A is an important tool for detecting and quantifying early CC alterations of DR.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.