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C. Macaluso, G. Bacchi, M. Camparini; Origin of Autofluorescence in Cystoid Macular Edema. A HRA Scanning Laser Ophthalmoscope and OCT Study . Invest. Ophthalmol. Vis. Sci. 2006;47(13):5665.
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© ARVO (1962-2015); The Authors (2016-present)
To verify whether the increased autofluorescence (AF) of retinal cysts observed in the foveal region of patients with cystoid macular edema (CME) is due to the lateral displacement of retinal tissue, with subsequent reduction in masking RPE–generated AF by macular pigment.
The Heidelberg Retina Angiograph (HRA) confocal scanning laser ophthalmoscope was used to acquire AF images of the macular region in 30 patients affected by CME of different origin. To improve signal to noise ratio, 4 to 32 30° HRA AF images at 512x512 pixel resolution were averaged. AF images clearly showed the intraretinal cysts as hyper–AF structures, corresponding to both fluorescein angiography and optical coherence tomography (OCT) scans, as previously reported (ARVO 2004). To verify the hypothesis that retinal tissue, hence macular pigment, is displaced by cysts, 5mm OCT3 scans were performed, intersecting cysts in the foveal area. Following correction for the different retinal magnification, relative AF intensity and "net retinal thickness" (i.e. retinal thickness minus cyst thickness) were measured on HRA and OCT images, respectively, at corresponding retinal locations .
When AF relative intensity was plotted against net retinal thickness, locations corresponding to cysts always appeared distinct from those corresponding to surrounding retinal areas unaffected by edema. Cyst locations showed high AF intensity and reduced net retinal thickness, while the opposite was true for unaffected retinal locations.To better describe the relationship between AF intensity and net retinal thickness, fine mapping of both measures in the foveal region was performed in 10 cases. The spatial distribution of AF intensity was highly correlated to the distribution of net retinal thickness, so that peaks in AF intensity always matched troughs in net retinal thickness.
The observed good correlation between AF intensity and net retinal thickness in the foveal region of eyes with cystoid macular edema tends to confirm the hypothesis that the origin of the hyper–AF of cysts does not represent a true increase in AF, but a descrease in masking of AF by macular pigment, that is reduced at the level of cysts due to the lateral displacement of retinal tissue.
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