Purpose
To assess the feasibility and proficiency of OCT-based microangiography (OMAG) in the detection and visualization of vascular involvement at different stages of age-related macular degeneration (AMD).
Methods
Twenty patients were recruited, including early stage AMD, geographic atrophy (GA), neovascular AMD and polypoidal choroidal vasculopathy (PCV). Patients were scanned by a Zeiss OCT-angiography prototype with motion tracking. OCT scans centered on the fovea were captured to generate the OMAG images. OMAG images were segmented into 4 layers including the inner (GCL->IPL), deeper (INL->photoreceptor layer) retinal layers, choriocapillaris, and deeper choroidal layer. Enface images were used to represent angiograms at different layers (coded with different colors for visual purposes).
Results
Enface OMAG images showed overall good agreement with fluorescein angiography (FA). OMAG gave more detailed visualization of vascular networks that were less affected by subretinal hemorrhages. In early stage AMD, small drusen were observed, but retinal vessels seemed the same as for normal subjects. For patients with GA, abnormalities of the RPE layer resulted in the ability to easily observe the choriocapillaris and large choroidal vessels. Feeding and draining vessels were identified in neovascular AMD and PCV. Choroidal neovascularization (CNV) was more demarcated by OMAG as compared to FA due to the late leakage of fluorescein dye which obscures the CNV.
Conclusions
OMAG provides depth-resolved and detailed vascular images of AMD. In most cases, proper segmentation is the key to identifying the location of abnormal vessels. Our ongoing studies with OMAG will standardize quantification of the retinal and choroidal vascular layers during the progression of AMD as well as following treatment, particularly with anti-VEGF agents.