Optical coherence tomography angiography during follow-up: qualitative and quantitative analysis of mixed type I and II choroidal neovascularization after vascular endothelial growth factor trap therapy.

PURPOSE: To report the optical coherence tomography angiography (OCT-A) findings in an exudative age-related macular degeneration (AMD) patient presenting mixed type I and II choroidal neovascularization (CNV) during follow-up after intravitreal vascular endothelial growth factor (VEGF) trap treatment.

METHODS: The clinical assessment included both traditional multimodal imaging, based on fluorescein angiography (FA), indocyanine green angiography (ICGA) and B-scan OCT, and OCT-A at baseline and follow-up. OCT-A images were obtained using a Spectralis OCT-A prototype able to acquire 70,000 A-scans per second, with a resolution of 7 µm axially and 14 µm laterally. An amplitude decorrelation algorithm developed by Heidelberg Engineering was applied to a volume scan, on a 15 × 5° area, which was composed of 131 B-scans (35 frames per scan) at a distance of 11 µm each. The borders of type I and type II CNV were manually outlined and then the areas were analyzed using the provided automated software before and after treatment.

RESULTS: The qualitative approach revealed a substantial decrease in the visibility of tiny branching vessels and anastomoses both in type I and type II components of the neovascular complex, associated with persistence of a clear hyperintense signal coming from the larger trunks, which remained well-perfused. Quantitative analysis confirmed a reduction of the lesion area after VEGF trap treatment: the type II component decreased from 0.25 to 0.19 mm(2), while the type I component decreased from 2.03 to 1.80 mm(2).

CONCLUSIONS: Our study qualitatively and quantitatively demonstrated the response of a mixed type I-II CNV to intravitreal VEGF trap therapy. Although FA remains the gold standard for determining the presence of leakage and OCT easily shows fluid accumulation and its variations, OCT-A offers noninvasive monitoring of the retinal and choriocapillaris microvasculature in patients with CNV, aiding in diagnosis and treatment decisions during follow-up.