Abstract
Abstract: :
Purpose: It was reported that fundus autofluorescence (AF) in patients with RP is characterized by the parafoveal ring of increased AF which travels towards the centre as the hypofluorescent atrophic changes expand from the periphery. The aim of this work was to evaluate the AF patterns in relation to retinal function, measured by electroretinography and visual field. Methods: :30 patients with RP were included in the study. AF imaging of the macular area was performed with the scanning laser ophthalmoscope. Patients were divided in two groups according to the pattern of fundus AF. In group 1 (n=20) all patients had a ring of increased AF of different size but no atrophic areas inside the vascular arcades. In group 2 (n=10) there were patients with narrow ring of increased AF and round atrophic changes at different distance from the fovea. Visual fields with kinetic and automated perimetry were taken, ISCEV PERG and mf ERG were recorded. The horizontal radius of the hyperfluorescent ring and the smallest radius of hypofluorescent areas from the fovea were compared to visual fields, PERG P50 and N95 and mf ERG average P1 amplitudes of the inner three concentric rings (inside 2.5 degrees, 2.5–8 degrees and 8–15 degrees). Results: In the group 1, a linear relationship was found between the radius of the hyperfluorescent ring and both the MS index of automated perimetry (r=0.68) and Goldmann II/4 average radius (r=0.88). The radius of the hyperfluorescent ring correlated highly with the PERG P50 (r=0.72) and N95 (r=0.74) amplitudes. Within the range of PERG stimulation area, the relation was linear. Mf ERG responses were reduced in all patients in all three rings (50, 32 and 24% of amplitude of normal mean), more towards the periphery. We could not find any strong relationship between the P1 amplitude of the central ring and the radius of the increased AF. The correlation between ring of AF and the amplitude of multifocal ERG was better for the rings 2 and 3. In the group 2, PERGs were non–recordable in all patients, mf ERG were preserved in some (n=5), but were very low (less then 25% of amplitude of normal mean). Also the radius of the hyper– or hypofluorescent changes did not correlate with any type of perimetry. Conclusions: Our results show that pattern of fundus autofluorescence correlates well with functional tests (perimetry, electroretinography) in early stages of the RP, before atrophic lesions appear inside the vascular arcades. This shows that AF imaging contains some information about retinal function and, being a quick and noninvasive method, AF can serve as a useful functional imaging tool in the follow–up of RP patients.
Keywords: retinal degenerations: hereditary • electroretinography: clinical • perimetry