Quantitative and Qualitative Analysis of Foveal Avascular Zone Characteristics in Different Stages of Diabetic Retinopathy Using Optical Coherence Tomography Angiography (OCT-A)

OCTA is superior to other retinal imaging techniques like fluorescein angiography(FA) as it does not require dye injection, Intravenous dye injection is time consuming and can have adverse side effects. Furthermore, the edges of the capillaries can become blurred due to dye leakage and imaging of the retina can only be 2D when using FA.

OCTA provides both structural and functional (i.e. blood flow) information in tandem. The "corresponding" OCT b-scans can be co-registered with the simultaneous OCT angiograms so the operator is able to scroll through the OCT angiogram like a cube scan. As a result, the precise location of pathology can be viewed on the corresponding OCT b-scans. This makes OCTA a better tool when detecting the exact location of a retinal pathology.

In diabetic retinopathy OCTA can show choriocapillaris abnormalities and/or retinal microvascular abnormalities such as microaneurysms, vascular remodeling adjacent to the foveal avascular zone (FAZ), enlarged FAZ, and capillary tortuosity and dilation through different stages. OCTA can show smaller vascular changes not detectable by FA.