Sp x1902

After all OCT-A scans were manually checked for artefacts, shadows and correct segmentation, macula data was exported from the clinical database and then imported into the prototype SP-X1902 software (Heidelberg Engineering, Heidelberg, Germany). The Anatomic Positioning System function (APS, part of Glaucoma Module Premium Edition [GMPE], Heidelberg Engineering, Germany) allows each scan to be aligned to the patient´s individual Fovea to Bruch’s Membrane Opening (FoBMOC) axis for better intra- and interindividual scan comparability. Integration of APS information was also implemented into the Erlangen Angio-Tool (EA-Tool) version 2.0, coded in Matlab (The MathWorks, Inc., R2017b). In addition to the APS information, the macular en face OCT-A images of SVP, ICP and DCP were imported into the EA-Tool and analyzed separately for each scan. Overall and sectorial macula VD (12 sectors s1-s12 á 30°) were analyzed for SVP, ICP and DCP, respectively. The analyzed region of the scan size was 6.10 mm².

OCT-A (Heidelberg Spectralis II, Heidelberg, Germany) is a diagnostic technique used to visualize retinal microcirculation in the macula and peripapillary region. Retinal macula microvasculature can be subdivided into three layers: the superficial vascular plexus (SVP), the intermediate capillary plexus (ICP) and the deep capillary plexus (DCP). All OCT-A scans have an angle of 15° covering a size of 2.9 mm × 2.9 mm, with a lateral resolution of 5.7 µm/pixel [5 (link)].
The OCT-A data were exported by the SP-X1902 software (prototype software, Heidelberg Engineering, Heidelberg, Germany) and analyzed by the Erlangen-Angio-Tool (EA-Tool) software, which is coded in MATLAB (The MathWorks, Inc., Natick, MA, USA, R2017b). Studies have revealed high levels of reliability and reproducibility for the EA-Tool [60 (link)]. For the analysis, VD was computed in 12 sectors of the macula. Moreover, overall VD was computed as a mean over the sectors. In addition, the Anatomic Positioning System (APS—part of Glaucoma Module Premium Edition (GMPE), Heidelberg Engineering, Heidelberg, Germany) was implemented in the EA-Tool. This feature aligns all OCT-A scans according to their individual fovea-to-Bruch’s membrane opening center axis (FoBMOC) to allow for a better comparison of different scans. This FoBMOC axis is defined by the fovea and the center of Bruch’s membrane opening [5 (link)].