Abstract
Purpose: :
The purpose of this study was to compare fundus autofluorescence (FAF) findings in patients with central serous chorioretinopathy (CSC) in various stages of disease imaged using a commercial scanning laser ophthalmoscopic (SLO) system (Heidelberg Spectralis, Heidelberg, Germany) and a fundus camera based system (Topcon America, Paramus, NJ).
Methods: :
Alterations in the retinal profile were evaluated by the SD-OCT and used to help evaluate potential differences in the FAF findings. The SLO system used a 488 nm laser excitation source and 500 nm barrier filter (488 nm AF). The fundus camera used a halogen lamp exciter with a 535-585 nm band-pass filter and a barrier bandpass filter at 605-705 nm.
Results: :
There were 23 eyes of 23 patients evaluated in this study. The images from the two systems showed similar, but not identical findings. The SLO system showed significant attenuation of autofluorescence in the central macula secondary to macular pigment in 11 eyes. Areas with subretinal fluid, particularly if there was accentuated material on the outer retina showed more hyperautofluorescence with the fundus camera system in 10 eyes. Some areas with previous subretinal fluid, which were resolved at the time of imaging showed relative hyperautofluorescence with the SLO system. These areas had loss of the outer segments when visualized with SD-OCT.
Conclusions: :
Although both methods of detecting FAF produced roughly similar images, there were differences that appear to be explainable by known retinal physiology. Decreased fluorescence from the central macula with the SLO system is likely secondary to macular pigment, the absorption spectrum of which is shorter than the excitation wavelengths used in the fundus camera. Areas of retinal detachment appear brighter in the fundus camera system probably because the precursors to lipofuscin that occur in the retina fluoresce at somewhat longer wavelengths. Some areas of previous detachment were more hyperautofluorescent with the SLO system; these areas colocalized with loss of the photoreceptor outer segments. The outer segments, particularly those of rods have been found to contain both lutein and Zeaxanthin, raising the possibility of the lack of pigment capable of absorbing the excitation light of the SLO instrument may lead to regional hyperautofluorescence.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • retinal pigment epithelium • retina