Near-Infrared Autofluorescence Imaging in Geographic Atrophy Using Spectralis Single and Combined Wavelength Modes

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PurposeThe Spectralis Heidelberg retina angiography + optical coherence tomography (OCT) device often fails to acquire near-infrared autofluorescence (NI-AF) due to poor signal because of interference by the beam splitter used for aligning the laser source with the OCT diode light source. We report the rates of successful NI-AF image acquisition using indocyanine green angiography (ICGA) mode (without dye) compared with combined fluorescein angiography (FA) + ICGA mode (without dye) in patients with geographic atrophy (GA).DesignThis was a retrospective review.MethodsTwo hundred images from 50 eyes of 25 patients with GA were included. All patients underwent NI-AF imaging using ICGA (787 nm) and combined FA + ICGA (488 + 787 nm) modes in both eyes. Each eye had macula- and disc-centered imaging. The rates of successful image acquisition were compared using McNemar test.ResultsSuccessful NI-AF acquisition using ICGA was 48% to 52% in macula-centered views and 36% to 56% in disc-centered views. Only 36% of patients had successful bilateral NI-AF imaging. This improved to 100% in all views in both eyes after switching to combined FA + ICGA mode (P < 0.001). Logistic regression showed no patient or ocular factors were predictive of NI-AF acquisition failure in ICGA mode.ConclusionsAcquisition of NI-AF images in GA using ICGA mode has a high failure rate, which can be eliminated by using combined FA + ICGA mode. This finding has implications on the design of imaging protocols for routine assessment and clinical trials of geographic atrophy.

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