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J.S. Kim, A. Manassakorn, H. Ishikawa, G. Wollstein, R.A. Bilonick, L. Kagemann, K. Sung, J.S. Duker, J.G. Fujimoto, J.S. Schuman; Comparison of Optic Disc Margin Identified by Planimetry and High Speed Ultrahigh–Resolution Optical Coherence Tomography (Spectral OCT, SOCT) . Invest. Ophthalmol. Vis. Sci. 2006;47(13):3642.
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© ARVO (1962-2015); The Authors (2016-present)
OCT defines the optic disc margin as the termination of the retinal pigment epithelium (RPE) layer. The purpose of this study was to test the hypothesis that OCT accurately measures the optic disc margin when compared to the planimetrically defined disc margin using conventional fundus camera and three dimensional SOCT.
Seventeen healthy subjects (17 eyes) had stereo optic disc photographs (DPs) and SOCT raster scans (180 frames, 501 samplings/frame) centered on the optic nerve head. Two image outputs were derived from the SOCT data set: an en–face OCT fundus image and a set of 180 frames of cross–sectional images. Three ophthalmologists independently marked the optic disc margin on the DP, en–face, and cross–sectional images in a randomized masked fashion using custom made software. One observer rotated, shifted, and scaled DPs to match the en–face image, and the disc margin markings were adjusted accordingly for all observers. Disc size (area, horizontal and vertical diameters) and location of the center of gravity were compared between DP and en–face and cross–sectional images.
The location of the center of gravity was similar among the three methods. Overestimation of disc size, in the cross–sectional images, was associated with peripapillary atrophy.
The optic disc margin as defined by OCT is significantly different than the margin defined by DP planimetry. The OCT cross–sectional definition overestimates the disc size due to the inclusion of peripapillary atrophy.
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