Macular OCT-angiography parameters to predict the clinical stage of nonproliferative diabetic retinopathy: an exploratory analysis

Abstract

Background: To test whether a single or a composite set of macular vascular density parameters, evaluated with optical coherence tomography angiography (OCTA), are able to predict nonproliferative diabetic retinopathy (NPDR) staging according to the gold-standard ETDRS-grading scheme.

Methods: Prospectively defined, cross-sectional study in which macular structural and vascular parameters of diabetic eyes with nonproliferative DR (up to ETDRS Level 53) were evaluated with OCTA (Avanti RTVue-XR 100, Optovue Inc, Fremont, CA). Seven-field photographs of the fundus were taken for DR staging according to the ETDRS-grading scheme. The vessel density in the superficial and deep capillary plexus (SCP and DCP, respectively), as well as in the choriocapillaris (CC), were calculated using automated software. Univariate and multivariate ordered logistic regression models were used in the analysis. P < 0.05 was considered statistically significant.

Results: We included 101 eyes from 56 subjects (mean (SD) age 62.64 (11.74) years; 57.4% were male). On univariate analysis, several OCTA parameters were found to be associated with higher ETDRS level (parafoveal SCP density: OR = 0.87 (95% CI 0.76-0.99), p = 0.039; parafoveal DCP density: OR = 0.79 (95% CI 0.72-0.87), p < 0.001; CC density: OR = 0.89 (95% CI 0.80-0.99)), p = 0.036). In the final model, while also adjusting for relevant clinical features, only parafoveal vessel density in the DCP remained as a significant predictor of NPDR ETDRS level (OR = 0.54 (95% CI 0.32-0.92), p = 0.024).

Conclusion: Our results suggest that parafoveal vessel density in the DCP is the parameter most robustly associated with ETDRS level. OCTA analysis may provide objective imaging biomarkers to monitor NPDR clinical progression.

Fig. 1

Macular vascular–vascular and neuro-vascular correlations in diabetic patients. Scatter plots of correlations for vascular vs. vascular a–c and neuronal vs. vascular d–h OCTA parameters in diabetic patients. For each correlation, a regression line with a 95% CI (shaded area) was fitted. The regression coefficient (R) and its respective P value are indicated on each plot. DCP. Deep Capillary Plexus. FAZ. Foveal Avascular Area. GCC. Ganglion Cell Complex. SCP. Superficial Capillary Plexus

Fig. 2

Representative OCTA scans of the deep capillary plexus (DCP) for each main ETDRS stage. Representative 3 × 3 mm macular OCTA scans of the DCP of diabetic patients with DR staged at ETDRS Levels 10 a, 20 b, 35 C, c and 47 A d. These scans depict how the capillary density within the DCP decreases in more-advanced stages of NPDR