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Peter Coombs, Joshua R. Ehrlich, Nathan M. Radcliffe; Peripapillary Atrophy Trajectory and Glaucoma. Invest. Ophthalmol. Vis. Sci. 2011;52(14):203.
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© ARVO (1962-2015); The Authors (2016-present)
Peripapillary atrophy (PPA) is found in both normal eyes and glaucoma eyes. This study evaluated PPA in normal and glaucoma eyes using a unique method of vector analysis.
71 patients under evaluation for glaucoma were included in the study (36 eyes with glaucoma, 35 normal eyes) each perimetrically defined with two reliable and repeatable SITA-Standard examinations using the Humphrey Field Analyzer II (Carl Zeiss Meditec, Dublin, CA). A 360 degree peripapillary scan was performed using standard protocol as for RNFL assessment using the Spectralis machine (Heidelberg Engineering, Heidelberg, Germany). PPA was evaluated by a single masked observer using optic nerve photographs. PPA width was measured at eight points surrounding the optic disc and a vector was derived from each, with the width serving as the magnitude. PPA trajectory was defined as the sum of those eight vectors. In addition, direction and angle of peripapillary optic disc tilt was calculated trigonometrically from OCT images using digital measurement software (Pixelstick, Pixelated Software). The maximum B-PPA width, location and total clock-hours were also recorded.
Glaucoma patients had significantly more clock hours of B-PPA and size of maximum B-PPA (8.7 vs. 4.9 clock hours; p<0.05 and 387 vs. 280 micrometers; p<0.05). PPA trajectory magnitude was not significantly different between the two groups (507 vs. 453 micrometers; p greater than 0.05). PPA trajectory direction in glaucoma patients was typically inferior/inferotemporal, while that of normal patients was relatively temporal and this difference was significant (p<0.01). Maximum PPA location between the two groups was not significantly different. The maximum area of B-PPA was significantly more aligned with the disc tilt in normal patients than in the glaucoma patients (35 vs. 73 degrees; p<0.01) Alignment of PPA trajectory and direction of optic disc tilt was similar. Angle and direction of disc tilt and spherical equivalence was similar.
This study presents a novel way of evaluating peripapillary atrophy, PPA trajectory, and shows potential for better differentiating glaucomatous and normal PPA trends.
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