Projection-Resolved Optical Coherence Tomography Angiography Parameters to Determine Severity in Diabetic Retinopathy

PURPOSE. The purpose of this study was to assess projection-resolved optical coherence tomography angiography (PR-OCTA) vessel density (VD) and foveal avascular zone (FAZ) in determining severity within diabetic retinopathy (DR) and their accuracy in identifying high-risk DR patients. METHODS. This was a retrospective study with 72 eyes of 52 DR patients, assessing the VD and FAZ area of the superficial capillary plexus (SCP) and deep vascular plexus (DVP), for both 3 x 3-mm and 6 x 6-mm scans between the DR groups (mild to moderate, severe and proliferative DR [PDR]). For accuracy, the severe and PDR groups were merged, representing the high-risk DR group for receiver operator characteristic analysis. VD of OCTA images with and without PR were compared. RESULTS. In mild to moderate, severe, and PDR groups, there were 31, 21, and 20 eyes, respectively. PR-OCTA improved VD analysis only in the DVP and particularly in advanced DR stages (P = 0.042). In the 3 x 3-mm PR scans, all superficial and deep parameters were significantly different between severe and PDR groups (P <= 0.020), but only the mean VD of SCP and DVP was also significant between the mild to moderate and severe groups (P <= 0.007). In the 6 x 6-mm scans, the superficial VD, deep VD, and superficial FAZ were significantly different between the severe and PDR groups (P <= 0.029). The superficial VD and deep VD of the 3 x 3-mm scans were good parameters for detecting high-risk patients (area under the curve = 0.829 and 0.895, respectively). CONCLUSIONS. PR-OCTA improved VD analysis of DVP. The 3 x 3-mm SCP and DVP VD were the most accurate in detecting high-risk DR.