Purpose:
To compare autofluorescence (AF) imaging via fundus camera (FC) and confocal scanning laser ophthalmoscope (cSLO).
Methods:
AF images were obtained with a digital FC, (Canon CX-1, Canon Inc, Tokyo, Japan), 530-580 nm excitation, 640 nm barrier filters, and a cSLO, (Heidelberg Retina Angiograph 2, Heidelberg engineering, Heidelberg, Germany), 488 nm exciter, 500 nm barrier. Images from both devices were evaluated by 2 authors. Correlation of AF pattern (hypo, iso, or hyper), atrophic lesion size (Matlab®, Mathworks, Natick, MA, USA), and image quality (forced choice) was studied. Acquisition time was noted.
Results:
We studied 120 eyes of 64 subjects, 35 male, 29 female, mean 62± 11 years. Diagnoses: age-related macular degeneration 62 eyes, diabetic retinopathy 6, pathologic myopia 5, macular hole 4, macular pucker 1, retinal dystrophy 24 (Stargardt, retinitis pigmentosa, maternally inherited diabetes and deafness, vitelliform dystrophy), and 8 normal.AF pattern correlated in 86% of lesions; by subtype: hemorrhage 100%, geographic atrophy (GA) 97%, flecks 82%, drusen 75%, exudates 70%, pigment epithelial detachment 67%, fibrous scars 50%, and macular hole 25%.Mean lesion size in GA was 4.57 ± 2.3mm2 via cSLO, 3.81 ± 1.94 mm2 via FC, (p<0.0001).Forced-choice image quality favored cSLO in 71%, FC in 26%. Acquisition time was 1/64 seconds via FC and 2.5 seconds via cSLO.
Conclusions:
AF images were highly correlated between the FC and cSLO. Differences in excitation wavelength and image acquisition revealed contrasts. Foveal mottling was imaged as discrete areas of hyper and iso-AF via FC, with diffuse hypo-AF in corresponding cSLO images, likely due to macular pigment absorption of short-wavelength excitation. Macular holes were iso-AF using the FC, yet distinctly hyper-AF via cSLO.GA lesions measured smaller with the FC than cSLO, in part due to a circumferential rim of hyper-AF in FC images, which may be lipofuscin accumulation in unhealthy retinal pigment epithelium cells.AF images were generally clear and diagnostic with both techniques. Multiple image capture and confocal optics yielded higher image contrast and signal-to-noise ratio with cSLO, though acquisition and exposure time was considerably longer.