NICE, France — OCT angiography, or OCT-A, is a large step forward in the diagnosis, follow-up and management of age-related macular degeneration, according to Gabriel Coscas, MD.
“In traditional OCT, for many years sub- or intraretinal fluid accumulation was a test of treatment efficacy to select the best schedule of intravitreal injections. Nevertheless, we know that a large number of patients remained in the group of nonresponders or partial responders in spite of multiple efforts. By directly analyzing activity criteria and blood flow in the CNV network before initial treatment and in the follow-up, OCT-A can guide us more effectively in our treatment and re-treatment decisions,” Coscas said at the Euretina meeting.
OCT-A allows specific 3-D visualization of retinal and choroidal vascularization. It consists of a fast succession of images in which the contrast between blood flow and static tissue is converted into an intensity signal, allowing visibility of the vascular bed without dye injection. Co-registered OCT B-scans provide additional morphological information, allowing identification of CNV and its localization in relation to the retinal pigment epithelium (RPE) and Bruch’s membrane (BM).
While an automatic segmentation might help for detection, a manual segmentation will be more precise for CNV analysis, Coscas said.
He suggested to “perform transverse section analysis or horizontally aligned to the RPE profile or BM profile, beginning above the RPE to identify pre-epithelial CNV, progressing in 30 µm layers between RPE and BM to image the entire subepithelial CNV network and finally towards the choroidal-scleral interface for feeder and draining vessels and for choroidal vessels and connections.”
“OCT-A is an evolving technology which is likely to become the method of choice to evaluate the activity or quiescence of the lesion and suggest treatment and re-treatment decisions, in any doubt, confirmed by the gold standard fluorescein angiography,” Coscas said. – by Michela Cimberle
Disclosure: Coscas reports he is a member of the advisory board of Allergan, Novartis, Bayer and Heidelberg Engineering.