The Effect of Software Versions on the Measurement of Retinal Vascular Densities Using Optical Coherence Tomography Angiography.

BACKGROUND

The goal of the study was to determine the effect of different software versions on the measurement of retinal vessel densities using optical coherence tomography angiography (OCTA) in normal subjects.

METHODS

Thirty-two eyes of eighteen healthy subjects were imaged using two OCTA devices: the Optovue RTVue and the Zeiss Cirrus. The macular 3 × 3 mm scan protocol was used. The images acquired using the Optovue OCTA device were exported using two different software versions in the system and compared to the images acquired through the Zeiss OCTA. In addition, the Optovue OCTA images were exported after manual adjustment of the segmentation boundaries according to the intraretinal layer definition. The densities of the superficial vascular plexus (SVP) and deep vascular plexus (DVP) were measured using fractal analysis by box-counting (Dbox).

RESULTS

Both the vessel densities of the SVP and DVP acquired using the Optovue OCTA device were significantly different when compared to those from the Zeiss OCTA device (all, <.05). No significant difference was found between the vessel densities of the SVP exported using both the new and old versions of Optovue ( >.05). However, the DVP exported using the new Optovue software version was significantly different compared to those exported using the old version ( <.05). The vessel densities of the SVP and DVP were related among the Optovue OCTA software versions and manual adjustment method (r ranged from 0.55 to 0.77; all <.05).

CONCLUSION

This is the first study to determine that different software versions with various intraretinal layer segmentation methods affect the vessel density measurements of the SVP and DVP.