Digital simultaneous fluorescein and indocyanine green angiography, autofluorescence, and red-free imaging with a solid-state laser-based confocal scanning laser ophthalmoscope.

Abstract

To describe and to evaluate a novel confocal scanning laser ophthalmoscope (cSLO) for fluorescence angiography, fundus autofluorescence (FAF), and red-free imaging. Digital infrared, red-free, FAF, fluorescein, and indocyanine green (ICG) angiography images were obtained with a cSLO in 766 patients. An optically pumped solid-state laser generates the excitation wavelength (488 nm) required for red-free, FAF, and fluorescein angiography images. For ICG angiography and infrared imaging, diode laser sources at 790 and 820 nm are used. Further features include an internal fixation control and a focus range of -24 to +30 diopters. High-image quality is achieved with a resolution of up to 5 microm per pixel in 30- x 30-degree images and allows for accurate delineation of normal and pathologic features. Simultaneous angiography offers high-contrast images. Corresponding display of quasi-simultaneous frames facilitates interpretation. A small focus difference between fluorescein and ICG scans occurs because of chromatic aberrations. Automated alignment and generation of mean images from several single frames allow for acquisition of high-resolution FAF images. Various laser-source related, optical, and electronic innovations improve cSLO fundus imaging for routine clinical application. A solid-state laser has advantages compared to argon gas laser sources, including less space occupation, heat emission, and noise production.