Quantitative Features of the Choriocapillaris in Healthy Individuals Using Swept-Source Optical Coherence Tomography Angiography

BACKGROUND AND OBJECTIVE: To quantify vessel density (VD) and grey value (GV) as a measure of flow in the choriocapillaris (CC) in healthy subjects with optical coherence tomography angiography (OCTA). PATIENTS AND METHODS: In this prospective, noncomparative case series, 3 mm x 3 mm OCTA images of 36 eyes of 22 healthy individuals were obtained using a swept-source instrument. VD and GV levels were calculated on CC en face slabs in the central 1-mm (subfoveal field) and surrounding 2.5-mm parafoveal ring. VD was calculated as a ratio of vessel area over nonvessel area following image binarization. GV was computed as the mean, un-normalized greyscale intensity value for all pixels in the region of interest. For each eye, the procedure was repeated 1 minute to 2 minutes later and intersession repeatability was analyzed. The choroidal thickness (CT) was automatically measured in the subfoveal and parafoveal regions and compared to VD and GV values. RESULTS: The VD ratio and GV was lower in the subfoveal field than in the parafoveal four sectors. The intersession intraclass correlation coefficients were high for both VD and GV measurements. There was no correlation observed between CT and VD or GV. CONCLUSIONS: Quantitative metrics can be obtained from CC OCTA en face images. These values show moderate to good intersession repeatability. These normative data may be of value as a reference of comparison in future studies of eyes with disease.