Figure 2

Presentation of image processing in three-dimensional optical coherence tomography angiography. (a) Schematic representation of an eye that has been cut open in order to provide a better explanation. In the posterior region, a brownish area is depicted, which corresponds to the location of the sharpest vision, the macula. Cross-sectional images of the macula in the area of the rectangle were captured from the same location. (b) These images correspond to structural OCT data that can be rendered into a volume representation. By repeatedly applying the same volume (here, two such volumes are shown as an example), the change in the OCT signal compared to the static tissue signal, which does not change much, can be interpreted as representing the blood flow. (c) Based on this, a common representation of the blood flow within the vessels can be shown via an en face image display method. Four such cross-sectional en face images are depicted here (each highlighted in green). However, as a trade-off between the amount of data and the processing, the intervening vessel parts are lost. (d) A three-dimensional rendering of the same data, showing the entire course of the vessels and their interrelationship. The rounded and vascular-free area in the center corresponds to the foveolar avascular zone (FAZ), in which the photoreceptors can interact as directly as possible with light.