Publication Review on the Use of OCT Angiography to Detect Active CNV
OCT angiography (OCT-A) is an emerging imaging modality with the potential to enhance the diagnostic understanding of various disease entities. It offers the possibility to visualize vascular networks in high-resolution and non-invasively as opposed to established imaging methods such as FA and ICGA angiography. In a recent publication1, Prof. Gabriel Coscas posed the important questions of if and how treatment decisions for patients with exudative AMD can already been guided by OCT-A findings.
How to identify patients with active choroidal neovascularization (CNV) based on OCT-A images?
Prof. Coscas and his team identified five criteria to identify an active CNV lesion (see figure below):
- Shape: A well-defined CNV lesion in contrast to one with long filamentous linear vessels.
- Branching pattern: Numerous tiny capillaries, typical of a recent lesion, in contrast to rare large mature vessels, typical of a mature one.
- Presence of anastomoses and loops.
- Morphology of the vessel termini, assessing the presence of a peripheral arcade in contrast to a “dead tree” appearance.
- Presence of a perilesional hypointense halo, considered as regions of choriocapillaris alteration.
How do treatment decisions based on OCT-A compare to those based on conventional fluorescence angiography?
The group examined a series of patients with classic FA and ICGA angiography, OCT and OCT-A. Treatment decisions based on either FA/ICGA plus OCT and OCT-A alone were compared.
This study demonstrated a high level of correspondence, in patients with exudative age-related macular degeneration, between different CNV patterns identified on OCT-A and treatment decisions established on conventional imaging. The authors concluded that, although fluorescein angiography remains the gold standard for determining the presence of leakage, and OCT shows fluid accumulation and its variations, OCT-A may offer non-invasive monitoring of the CNV, aiding for each treatment decision during the follow-up. However, the authors also point to the challenge that doctors face to fully understand the vascular networks in OCT-A images and to reliably identify the OCT-A parameters in order to diagnose an active CNV.
1Coscas et al. Optical Coherence Tomography Angiography versus traditional multimodal imaging in assessing the activity of exudative age-related macular degeneration. A new diagnostic challenge. RETINA 2015; 35:2219–2228.