Topographic analysis of retinal and choroidal microvasculature according to diabetic retinopathy severity using optical coherence tomography angiography

To investigate the topographic changes in the retinal capillary plexus and the choriocapillaris according to the severity of diabetic retinopathy (DR) using optical coherence tomography angiography (OCTA).

Subjects were recruited and classified into one of the following four groups: normal controls (n = 52), diabetes without DR (n = 49), non-proliferative DR (n = 51) and proliferative DR (n = 38). Using OCTA, the superficial capillary plexus (SCP), deep capillary plexus (DCP) and the choriocapillaris vessel densities were measured and compared in different macular areas: the fovea (1-mm diameter circular area), parafovea (1–3-mm diameter ring) and perifovea (3–6-mm ring).

With DR progression, vessel densities in the SCP and DCP as well as the choriocapillaris decreased, while the foveal avascular zone area increased (p < 0.001 for all). Compared with controls, the SCP and DCP vessel densities of the diabetes without DR group were decreased in all areas of the macula (p < 0.020 for all), while the choriocapillaris vessel density was decreased only in the perifoveal area (p = 0.823 for the foveal area; p = 0.631 for the parafoveal area; p = 0.039 for the perifoveal area). Multivariate linear regression analyses revealed that all retinal and choroidal microvascular indices were significantly associated with the DR severity.

The morphological changes in the macular microvasculature were associated with DR severity. Also, the changes were found to be more vulnerable in the retinal capillary plexuses than the choriocapillaris.