Novel interpretation of fundus autofluorescence (FAF) findings in choriocapillaritis

Purpose To determine the significance of increased fundus autofluorescence (FAF488) in choriocapillaritis, comparing photobleaching process, SD-OCT and melanin-related fundus autofluorescence (FAF787) findings Methods FAF488 signal depends on both the amount of bisretinoids in the RPE and the absorbion of light by photoreceptor pigments, macular pigment and RPE melanin. During the photobleaching process (absorbion of photons by photopigment in the outer photoreceptor segments), there is a reduction of the photopigment density and so an increase of the visualization of the autofluorescent signal Results In MEWDS and MFC, the more striking FAF488 alteration is an increase of the autofluorescent signal and SD-OCT shows a disruption of IS/OS junction, probably sign of dismanting outer photoreceptor segments; there is not an increase of FAF787 and after the photobleaching process, the areas of increased FAF488 become isofluorescent. This could mean that the areas of hyperautofluorescence are due to a better visualization of the autofluorescent signal because there is a reduction of the visual pigments and not to an increase of the fluorophores. In the APMPPE group, during the convalescent stage, increased FAF488 and FAF787 are often seen in the center of chorioretinal scars, corresponding to accumulation of fuorophores debris and to hypertrophy/hyperplasia of RPE cells Conclusion In MEWDS and MFC, photobleaching process, FAF787 and spectral-domain OCT findings may explain the increased FAF488 present in the acute phase of the diseases as a loss of the photopigments and not to an increase of fluorophores, because there is a limited pertubation of choriocapillaris circulation with a slight ischaemic insult to outer retina.