Dark halo, a new biomarker in macular neovascularization: comparison between OCT angiography and ICGA-a pilot prospective study

Purpose: To compare optical coherence tomography angiography (OCTA) and indocyanine green angiography (ICGA) in terms of reliability in detecting dark halo in patients affected by age-related macular degeneration (AMD) complicated with type 1 macular neovascularization (MNV). Methods: Eighty-nine eyes of 89 patients were analyzed at the University of Naples Federico II between January 2018 and October 2021. Each patient underwent a complete ophthalmological evaluation including fluorescein angiography, ICGA, spectral domain optical coherence tomography (SD-OCT), and OCTA. OCTA and ICGA images of dark halo were compared. The paired Student's test and intraclass correlation coefficients were used to evaluate the differences in dark halo measurements between OCTA and ICGA images. Results: Thirty-six eyes of 36 patients were included in this prospective study. Dark halo area was significantly larger in OCTA than in ICGA (1.49 ± 1.8 mm2 vs. 0.54 ± 0.5 mm2; p = 0.001). Moreover, the agreement between the two types of devices for measuring dark halo areas was poor, with a low intraclass coefficient correlation (0.397). Conclusion: OCTA could be a useful and necessary tool to investigate dark halo in neovascular AMD due to its ability to visualize the areas of reduced vessel density around MNV in greater detail compared to ICGA. Clinical trial registration: ClinicalTrials.gov Identifier: NCT05108285.