Abstract
Purpose :
OCT angiography (OCT-A) enables a detailed examination of the internal structure of choroidal neovascularization (CNV). Because OCT-A images represent different gray values, a mathematical characterization of the CNV structure may be possible. The aim of the study was to develop a mathematical characterization of the vascular morphology of CNV and to investigate changes under anti-VEGF therapy.
Methods :
In 25 patients, the initial diagnosis of an exudative AMD was made using FA and SD-OCT. In addition, OCT-A imaging (Avanti/FA Optovue) was performed initial and after the first cycle of anti-VEGF therapy on all patients. The OCT-A datasets were exported to an external image processing program and a vessel skeletonization was created by means of edge detection. Based on this, the total vessel length, the number of individual segments and the fractal dimension (FD) of the CNV were calculated before and after therapy.
Results :
A total of 14 type 1 CNV and 16 type 2 CNV are evaluated. The total vessel length of the CNV showed a significant reduction under anti-VEGF therapy (mean value 652 pixels v. s. 397 pixels; p < 0.0001), as well as the number of individual vessel segments of the CNV (mean value 117 v. s. 76; p < 0.0001). The CNV's FD showed a significant reduction under therapy (mean value 1.23 v. s. 1.16, p < 0.0001).
Conclusions :
By means of edge detection with quantification of vessel length, the number of individual segments and the FD an objective analysis of the vascular morphology of CNV is possible. A reduction in CNV under anti-VEGF therapy has been shown and the decrease in FD indicates a reduction in the complexity of the vascular structure. Especially the FD could be a biomarker for the activity assessment of CNV in the future.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.