Pre-injection fluorescence in indocyanine green angiography.

Abstract

To verify whether infrared pre-injection fluorescence can be observed in patients undergoing indocyanine green (ICG) angiography. Infrared fundus photographs were taken before dye injection for 450 consecutive patients undergoing ICG angiography for different chorioretinal disorders. The authors used a high-resolution videoangiography system with the standard ICG filters inserted (overlap, < 0.5%) and the highest flash intensity. Pre-injection fluorescence was detected in 184 patients (40.8%). It was a strong fluorescence in 75 patients (40.7%) and a faint fluorescence in 109 (59.2%). When fluorescence was strong, it simulated vascular filling on the ICG angiogram. Pre-injection fluorescence resulted from the following lesions: (1) old grayish subretinal hemorrhages (35 patients); (2) lipofuscin-like deposits (65 patients); (3) pigmented choroidal neovascular membranes (72 patients); and (4) serous retinal detachments lasting from several months or years (12 patients). Highly reflecting white lesions were not fluorescent. Pre-injection fluorescence of chorioretinal lesions is frequently detectable in patients with diseases requiring ICG examination. A pre-injection photograph may help to avoid misinterpretation of the angiograms. The authors' findings may be interpreted as pseudofluorescence or autofluorescence. Pigments contained in pathologic structures of the ocular fundus may be the source of autofluorescence emissions in the near-infrared range.