Swept-source and spectral domain optical coherence tomography angiography versus dye angiography in the measurement of type 1 neovascularization

PURPOSE: To compare the area of Type 1 neovascularization in patients with age-related macular degeneration calculated on spectral domain optical coherence tomography angiography (SD-OCTA), swept-source OCTA, and indocyanine green angiography (ICGA). METHODS: Cross-sectional study enrolling patients with neovascular age-related macular degeneration with Type 1 neovascularization. During the same visit, ICGA (Spectralis HRA, Heidelberg, Germany), 3 × 3-mm or 6 × 6-mm SD-OCTA (CIRRUS AngioPlex model 5000; Carl Zeiss Meditec, Inc, Dublin, OH), and 3 × 3-mm or 6 × 6-mm swept-source OCTA (Plex Elite 9000; Carl Zeiss Meditec, Inc) were performed. Neovascularization areas were compared among the three instruments. The degree of consistency between measurements was investigated through the two-way mixed intraclass correlation, whereas the intermethod agreement was expressed by the Bland-Altman analysis. Mean difference and 95% confidence intervals are provided. RESULTS: Eighteen eyes of 14 white patients (10 females, 83.3%) were included in the study. The neovascularization area measured on ICGA was higher compared to that measured on both SD-OCTA (P = 0.008) and swept-source OCTA (P = 0.008), whereas no differences were found between the two OCTA. Similar results were achieved analyzing 3 × 3-mm and 6 × 6-mm scan separately. Lowest reliability resulted from the ICGA versus SD-OCTA pair (intraclass correlation = 0.786, confidence interval = 0.500-0.915). Spectral domain OCTA and swept-source OCTA exhibited an excellent agreement (mean difference = 0.2). Swept-source OCTA offered qualitatively better images of the neovascularization, compared with SD-OCTA. CONCLUSION: Better visualization of the extent of neovascularization is obtained using SS-OCT or SD-OCT compared with ICGA, which may be influenced by choroidal permeability and dye leakage. Neovascularization area on OCTA may become an objective parameter in the follow-up of age-related macular degeneration patients, along with traditional imaging techniques