Variance Owing to Observer, Repeat Imaging, and Fundus Camera Type on Cup-to-disc Ratio Estimates by Stereo Planimetry

Kwon, Young H.; Adix, Michael; Zimmerman, M. Bridget; Piette, S; Greenlee, Emily C.; Alward, Wallace L.M.; Abràmoff, Michael D.

doi:10.1097/ijg.0b013e318181545e

Cited by 23 publications

(30 citation statements)

References 13 publications

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“…In this study, the reference standard was set by a single expert. We have previously shown that there is substantial interobserver variability of planimetry of the optic disc in stereo color fundus photographs [2]. By training the automatic method on the segmentations from a single expert observer, the method produces results that are biased towards the opinion of this observer.…”

Section: Discussionmentioning

confidence: 99%

“…The ratio of the optic disc cup and rim surfaces, or cup-to-disc ratio in these images is an important structural indicator for assessing the presence of glaucoma and may help in quantifying the progression of glaucoma. To quantify the ratio, planimetry has commonly been performed by glaucoma specialists from stereo color photographs of the optic disc [2]. However, we and others have previously shown that manual planimetry is time-consuming with substantial interobserver variability [2].…”

Section: Introductionmentioning

confidence: 99%

“…To quantify the ratio, planimetry has commonly been performed by glaucoma specialists from stereo color photographs of the optic disc [2]. However, we and others have previously shown that manual planimetry is time-consuming with substantial interobserver variability [2]. With the introduction of spectral-domain optical coherence tomography (SD-OCT) scanners [3], [4], some of which are capable of acquiring close-to-isotropic 3-D ONH-centered volumes (Fig.…”

Section: Introductionmentioning

confidence: 99%

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Segmentation of the Optic Disc in 3-D OCT Scans of the Optic Nerve Head

Lee

Niemeijer

Garvin

et al. 2010

IEEE Trans. Med. Imaging

145

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Glaucoma is the second leading ocular disease causing blindness due to gradual damage to the optic nerve and resultant visual field loss. Segmentations of the optic disc cup and neuroretinal rim can provide important parameters for detecting and tracking this disease. The purpose of this study is to describe and evaluate a method that can automatically segment the optic disc cup and rim in spectral-domain 3-D OCT (SD-OCT) volumes. Four intraretinal surfaces were segmented using a fast multiscale 3-D graph search algorithm. After surface segmentation, the retina in each 3-D OCT scan was flattened to ensure a consistent optic nerve head shape. A set of 15 features, derived from the segmented intraretinal surfaces and voxel intensities in the SD-OCT volume, were used to train a classifier that can determine which A-scans in the OCT volume belong to the background, optic disc cup and rim. Finally, prior knowledge about the shapes of the cup and rim was incorporated into the system using a convex hull-based approach. Two glaucoma experts annotated the cup and rim area using planimetry, and the annotations of the first expert were used as the reference standard. A leave-one-subject-out experiment on 27 optic nerve head-centered OCT volumes (14 right eye scans and 13 left eye scans from 14 patients) was performed. Two different types of classification methods were compared, and experimental results showed that the best performing method had an unsigned error for the optic disc cup of 2.52±0.87 pixels (0.076±0.026 mm) and for the neuroretinal rim of 2.04 ± 0.86 pixels (0.061 ± 0.026 mm). The interobserver variability as indicated by the unsigned border positioning difference between the second expert observer and the reference standard was 2.54 ± 1.03 pixels (0.076 ± 0.031 mm for the optic disc cup and 2.14 ± 0.80 pixels (0.064 ± 0.024 mm for the neuroretinal rim. The unsigned error of the best performing method was not significantly different (p > 0.2) from the interobserver variability.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Segmentation of the Optic Disc in 3-D OCT Scans of the Optic Nerve Head

Lee

Niemeijer

Garvin

et al. 2010

IEEE Trans. Med. Imaging

145

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“…3 However, we and others have previously shown that manual planimetry is time-consuming and introduces substantial inter-observer variability due to the need for human interpretation. 4,5 Merickel et al developed a 2-D automated system for the segmentation of the optic disc margin (and cup) on stereo fundus disc photographs. 6 They used a soft pixel classification method to generate a probability map of the disc and segmented the disc using a graph search method upon the probability map image.…”

Section: Introductionmentioning

confidence: 99%

Automated segmentation of the optic disc margin in 3-D optical coherence tomography images using a graph-theoretic approach

Niemeijer

Lee

et al. 2009

Medical Imaging 2009: Biomedical Applications in Molecular, Structural, and Functional Imaging

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The optic disc margin is of interest due to its use for detecting and managing glaucoma. We developed a method for segmenting the optic disc margin of the optic nerve head (ONH) in spectral-domain optical coherence tomography (OCT) images using a graph-theoretic approach. A small number of slices surrounding the Bruch's membrane opening (BMO) plane was taken and used for creating planar 2-D projection images. An edgebased cost function -more specifically, a signed edge-based term favoring a dark-to-bright transition in the vertical direction of polar projection images (corresponding to the radial direction in Cartesian coordinates) -was obtained. Information from the segmented vessels was used to suppress the vasculature influence by modifying the polar cost function and remedy the segmentation difficulty due to the presence of large vessels. The graph search was performed in the modified edge-based cost images. The algorithm was tested on 22 volumetric OCT scans. The segmentation results were compared with expert segmentations on corresponding stereo fundus disc photographs. We found a signed mean difference of 0.0058 ± 0.0706 mm and an unsigned mean difference of 0.1083 ± 0.0350 mm between the automatic and expert segmentations.

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“…It has been suggested that use of visual estimation for assessment of infected toenails may be a source of error in determining onychomycosis efficacy (1,2). Significant intra-observer differences have been noted in assessments of nail disease characteristics, as well as other medical fields (3)(4)(5). Despite the issues with visual assessment, few published works support the need for objective measures of affected areas in onychomycosis, or illustrate the validity of objective solutions (1).…”

Section: Introductionmentioning

confidence: 97%

Comparison of visual assessments versus planimetry assessments in a large-scale clinical trial of onychomycosis

Gupta

Cooper

2012

Journal of Dermatological Treatment

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Variance Owing to Observer, Repeat Imaging, and Fundus Camera Type on Cup-to-disc Ratio Estimates by Stereo Planimetry

Abstract: Interobserver variability was the largest source of variation for glaucoma specialists, whereas their interrepeat and intercamera variability is comparable with that of the algorithm. DAP reduces variability on LCDR estimates from simultaneous stereo images, such as the Nidek 3Dx.

Cited by 23 publications

References 13 publications

Segmentation of the Optic Disc in 3-D OCT Scans of the Optic Nerve Head

Segmentation of the Optic Disc in 3-D OCT Scans of the Optic Nerve Head

Automated segmentation of the optic disc margin in 3-D optical coherence tomography images using a graph-theoretic approach

Comparison of visual assessments versus planimetry assessments in a large-scale clinical trial of onychomycosis

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