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G. Staurenghi, C. Keilhauer, F. Viola, P. Salvetti, D. Goger, F. Delori; Variability in Macular Pigment Distribution Evaluated by Autofluorescence Imaging . Invest. Ophthalmol. Vis. Sci. 2003;44(13):5118.
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Purpose: Macular pigment (MP) observed in blue light is seen as 0-3° diameter dark spot centered on the fovea. This is also the case in autofluorescence (AF) imaging with blue excitation, but some subjects also exhibit a 1°-diameter annulus of lighter darkness around the central peak, within the extent of the MP distribution. We investigated the frequency in which this ring-pattern is observed in ophthalmoscopically normal eyes. Methods: 57 patients without ocular pathology were examined in two different centers: 39 patients in Wuerzburg (Germany) and 18 in Brescia (Italy). Mean age was 60 years (30-81 years) equally distributed among female and male (p=0.14). AF images (488 nm excitation; 30 or 20°) were recorded for each eye using Confocal Scanning Laser Ophthalmoscopes (Heidelberg Retinal Angiograph, Heidelberg Engineering GmbH, Dossenheim, Germany). Four independent readers evaluated AF images (49 right eyes and 44 left eyes), masked for gender and age. Each assessed whether a ring-pattern was present or not. Results: There was significant inter-reader agreement in observing the ring-pattern for all but one of the 12 comparisons (2 eyes, Chi2=2.1-24.9). The ring was seen in 34 to 55% of the eyes. This rate was not affected by gender of the patients (p>0.3, for both eyes), by age (p>0.15), or by testing site (p>0.6). Diameter of the centerline of the ring measured micro-metrically in 15 subjects was 1.3 ± 0.2° horizontally and 1.1 ± 0.2° vertically, with a significant elliptically (p<0.0001). For subjects where both eyes were examined (n=36), there was good inter-ocular correspondence in observing the pattern (Chi2=36, p=0.002). Conclusions: The main factors affecting the visibility of pattern is the extent of the MP distribution and the fact that the ring position is relatively constant. Thus, the ring pattern is seen if the MP extends beyond an eccentricity of about 0.6°, but not in the opposite case. Similar bimodal distributions of MP were observed in primate retinas (Snodderly, 1984). The observed individual variations in the MP distribution may be caused by variability in the amount of MP and in the anatomical dimensions of the fovea and its depression.
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