OCT Angiographic Findings in Retinal Angiomatous Proliferation

OCT angiography (OCT-A) allows non-invasive blood flow registration of the retina and choroid. In contrast to fluorescein angiography (FA), no dye has to be administered. The OCT-A also provides depth-selective information. OCT-A and FA were compared in patients with neovascular age-related macular degeneration (AMD) with retinal angiomatous proliferation (RAP) stage 1. In stage 1, the neovascularizations are intraretinal. In contrast to the two-dimensional total image of the FA, the OCT-A allows a depth-selective display of the individual retinal layers. In this way, a conclusion can be drawn about the place of origin of the RAP.

Three patients with neovascular AMD and RAP stage 1 were included. They were examined with OCT (ZEISS CIRRUS HD-OCT 5000, Carl Zeiss Meditec, Inc., Dublin, USA), OCT-A (ZEISS AngioPlex OCT-Angiography) as well as FA (HRA2, Heidelberg Engineering) between January 2016 and March 2019. A complete ophthalmological examination was performed. A qualitative analysis of the OCT-A images (3 × 3 and 6 × 6 mm) and the FA images was carried out. Leaks in the FA were compared with the en-face images of the OCT-A followed by a depth-selective assignment using the corresponding B-scans of the OCT-A.

It was one woman and two men aged 66 - 89 years. The visual acuity was 0.4 in the first, 0.5 p in the second and 0.8 in the third patient. The diagnosis of RAP stage 1 could be made both in the OCT, the FA and the OCT-A. All patients showed macular edema in the OCT. The FA showed selective hyperfluorescence in the early phase and fluorescein extravasation in the late phase. In OCT-A, the blood flow in all patients could be shown in the hyperreflective structure of the RAP in the B-scan. The first patient showed two RAP lesions in the FA, which were in the deep vascular plexus in the OCT-A. In the second patient, three RAP lesions were found in the FA, and a total of five RAP lesions in the OCT-A. One could be located in the superficial and deep vascular plexus, four in the deep vascular plexus. The third patient showed one RAP lesion in the FA as well as in the OCT-A, which could be assigned to the superficial vascular plexus.

The OCT-A is well suited for the diagnosis of RAP stage 1. In the present cases, the diagnosis in the OCT-A could be made as clearly as by FA. A major advantage of the OCT-A results from the non-invasive character and the depth selectivity. The RAP 1 lesions could be assigned to both the superficial and the deep vascular plexus. Depth selection is not possible with the FA due to the summary picture.