OCTA (Optical Coherence Angiography Tomography) Versus Structural OCT(Optical Coherence Tomography) in Neovascular AMD (Age Macular Degeneration)

Overview

The objective is to find if there is a relationship between the Fractal Dimension, the gap, vascular density (VD), the surface, the span ratio and the status of the choroidal neovessels to adjust the interval between 2 intravitreal injections nor on the qualitative aspect of Optical Coherence Structural Tomography but also on quantified quantitative and objective values.

This quantification is based on the analysis of fractal dimension (FD, without unit), lacunarity (Lac, without unit), vascular density (VD,%) and surface area of choroidal neovascular ( CNV, mm2). The fractal dimension of a vascular structure corresponds to its degree of complexity. Fractals are models found in nature and biological systems that show self-similarity at different magnifications. It is obtained from the "box counting" method calculating the number of vascular segments contained in squares of varied size. Normal retinal vessels have a known and quantified complexity (FD = 1.7). A neovascular tumor treated with anti-angiogenics will reduce vascular density, losing its random architecture; the investigators observe a return to a model standardized. NVCs have a random organization. The lower the FD, the more random the vascular architecture. Lacunarity represents the texture or the homogeneity of a lesion, this one is heterogeneous when it is little vascularized and homogeneous if the vascularization is very dense. The lower the lake, the more homogeneous the lesion. FD and Lac are obtained in Angiography Optical Coherence Tomography (OCTA) by the analysis of the hypersignal detected on the cut of the external retina. The image is automatically binarised and skeletonized. NVC delineation is automatic and associated with automatic background noise processing. This software is fully automatic whose inter and intra grader reproducibility will be evaluated.

Conditions