ABSTRACT
INTRODUCTION Autofl uorescence (AF) is the emission of light by a natural substance (e.g., lipofuscin) after being stimulated by excitation energy. AF is distinguished from fl uorescence that is the emission of light by an artifi cial molecule (e.g., fl uorescein). Fundus AF was fi rst recognized from control photographs taken prior to the injection of fl uorescein dye during fl uorescein angiography. The AF signal seen from normal patients was minimal, whereas increased AF was recognized from patients with abnormalities such as optic nerve drusen, Best’s macular dystrophy, and Stargardt’s disease (1). Fundus AF imaging was diffi cult with conventional photography due to the low levels of light emitted using the standard fi lter sets used for fl uorescein angiography. The development of the fundus spectrophotometer allowed for the measurement of emission spectra from the fundus sampled in 2-3° diameter retinal fi elds (2). Fundus AF was found to be emitted in a broad spectrum between 500 and 750 nm with a maximum of approximately 630 nm. The optimal excitation wavelength was approximately 510 nm (2). The AF signal was highest at 7-15° from the fovea with a minimum at the fovea (2). Today, fundus AF imaging can be achieved with a scanning laser ophthalmoscope (SLO) or a modifi ed fundus camera with special fi lter sets.
