Fluorescein angiography-guided indocyanine green angiography for the detection of feeder vessels in subfoveal choroidal neovascularization

Aims To compare the newly devised fluorescein angiography (FA) - guided indocyanine green angiography (ICGA) with conventional ICGA for detecting feeder vessels in subfoveal choroidal neovascularization (CNV). Methods The detection of feeder vessels was attempted in 86 AMD patients with subfoveal CNV: 44 (age 70.4 +/- 4.5 years) underwent conventional ICGA ( control group) and 42 (age 70.9 +/- 4.0 years) underwent an FA-guided ICGA (FA-guided group) using a double-detector scanning laser ophthalmoscope (SLO). In the control group, indocyanine green (ICG) was injected simultaneously with fluorescein. The patients were instructed to gaze forward localizing the fovea at the centre. In the FA-guided group, fluorescein sodium was injected a few minutes prior to ICG, and the patients were instructed to fixate in the appropriate direction by referring to the ongoing FA on the monitoring screen. In both groups, a 201 visual angle was used to capture good images of feeder vessels in ICGA and, in case ICGA missed the first images of the entire CNV filling, an additional injection of ICG was given in the late phase to record the choroidal filling again. The overall detection rate, single-injection detection rate, double-injection rate and examination time were analysed using Fisher's direct exact probability test or Mann Whitney's U-test. Results There was no significant difference in the overall detection of feeder vessels between the two groups (50% in the control group and 52.3% in the FA-guided group; P = 0.49 with Fisher's direct exact probability test). However, in the FA-guided group, the single injection detection rate was significantly higher (45.1 and 15.9%, respectively; P<0.001 with Fisher's direct exact probability test); significantly less double injections were required (7.1 and 50%, respectively; P = 0.003 with Fisher's direct exact probability test); and significantly shorter examination times were needed (9.6 +/- 3.7 and 14.1 +/- 6.8 min, respectively; P = 0.02 with Mann - Whitney's U-test). Conclusion FA-guided ICGA is effective for detecting feeder vessels of subfoveal CNV, minimizing the amount of ICG injected and the examination time compared to conventional ICGA.