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Automated volumetric evaluation of stereoscopic disc photography.

Xu J, Ishikawa H, Wollstein G, Bilonick RA, Kagemann L, Craig JE, Mackey DA, Hewitt AW, Schuman JS - Opt Express (2010)

Bottom Line: Disc area, rim area, cup area, cup/disc area ratio, vertical cup/disc ratio, rim volume and cup volume were automatically computed by the algorithm.AP had better reproducibility for disc area and cup volume and worse reproducibility for cup/disc area ratio and vertical cup/disc ratio, when the measurements were compared to the MP, SLO and OCT methods.AP provides a useful technique for an objective quantitative assessment of 3D ONH structures.

View Article: PubMed Central - PubMed

Affiliation: UPMC Eye Center, Ophthalmology and Visual Science Research Center, Eye and Ear Institute, Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.

ABSTRACT

Purpose: To develop a fully automated algorithm (AP) to perform a volumetric measure of the optic disc using conventional stereoscopic optic nerve head (ONH) photographs, and to compare algorithm-produced parameters with manual photogrammetry (MP), scanning laser ophthalmoscope (SLO) and optical coherence tomography (OCT) measurements.

Methods: One hundred twenty-two stereoscopic optic disc photographs (61 subjects) were analyzed. Disc area, rim area, cup area, cup/disc area ratio, vertical cup/disc ratio, rim volume and cup volume were automatically computed by the algorithm. Latent variable measurement error models were used to assess measurement reproducibility for the four techniques.

Results: AP had better reproducibility for disc area and cup volume and worse reproducibility for cup/disc area ratio and vertical cup/disc ratio, when the measurements were compared to the MP, SLO and OCT methods.

Conclusion: AP provides a useful technique for an objective quantitative assessment of 3D ONH structures.

Show MeSH
: Geometric model of optic nerve head (ONH) with cross sectional profile and projected image. (A) Locating cup margin points in deformable model algorithm. (B) Cross sectional profile of 3D ONH model, with definitions of various ONH parameters, i.e., disc area, rim area, cup area, rim volume and cup volume. (C) The definitions of vertical C/D ratio and C/D area ratio.
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g004: : Geometric model of optic nerve head (ONH) with cross sectional profile and projected image. (A) Locating cup margin points in deformable model algorithm. (B) Cross sectional profile of 3D ONH model, with definitions of various ONH parameters, i.e., disc area, rim area, cup area, rim volume and cup volume. (C) The definitions of vertical C/D ratio and C/D area ratio.

Mentions: The geometrical center of the region with the highest intensity value on the image was located as the disc center. The disc margin was generated using a deformable model technique whereby a smooth boundary of high contrast surrounding the disc center was detected (Fig. 1C). The image features, such as pixel intensity value, gradient, and contour smoothness, were extracted and used in computation of the deformable model [6]. The cup was located at 150μm posterior to the disc margin for eyes where 0.2mm ≤ cup depth ≤ 1.0mm, or at the 1/5 depth from the disc margin to the deepest point of the cup for eyes with cupping < 0.2mm or > 1.0mm (Fig. 4AFig. 4


Automated volumetric evaluation of stereoscopic disc photography.

Xu J, Ishikawa H, Wollstein G, Bilonick RA, Kagemann L, Craig JE, Mackey DA, Hewitt AW, Schuman JS - Opt Express (2010)

: Geometric model of optic nerve head (ONH) with cross sectional profile and projected image. (A) Locating cup margin points in deformable model algorithm. (B) Cross sectional profile of 3D ONH model, with definitions of various ONH parameters, i.e., disc area, rim area, cup area, rim volume and cup volume. (C) The definitions of vertical C/D ratio and C/D area ratio.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2913866&req=5

g004: : Geometric model of optic nerve head (ONH) with cross sectional profile and projected image. (A) Locating cup margin points in deformable model algorithm. (B) Cross sectional profile of 3D ONH model, with definitions of various ONH parameters, i.e., disc area, rim area, cup area, rim volume and cup volume. (C) The definitions of vertical C/D ratio and C/D area ratio.
Mentions: The geometrical center of the region with the highest intensity value on the image was located as the disc center. The disc margin was generated using a deformable model technique whereby a smooth boundary of high contrast surrounding the disc center was detected (Fig. 1C). The image features, such as pixel intensity value, gradient, and contour smoothness, were extracted and used in computation of the deformable model [6]. The cup was located at 150μm posterior to the disc margin for eyes where 0.2mm ≤ cup depth ≤ 1.0mm, or at the 1/5 depth from the disc margin to the deepest point of the cup for eyes with cupping < 0.2mm or > 1.0mm (Fig. 4AFig. 4

Bottom Line: Disc area, rim area, cup area, cup/disc area ratio, vertical cup/disc ratio, rim volume and cup volume were automatically computed by the algorithm.AP had better reproducibility for disc area and cup volume and worse reproducibility for cup/disc area ratio and vertical cup/disc ratio, when the measurements were compared to the MP, SLO and OCT methods.AP provides a useful technique for an objective quantitative assessment of 3D ONH structures.

View Article: PubMed Central - PubMed

Affiliation: UPMC Eye Center, Ophthalmology and Visual Science Research Center, Eye and Ear Institute, Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.

ABSTRACT

Purpose: To develop a fully automated algorithm (AP) to perform a volumetric measure of the optic disc using conventional stereoscopic optic nerve head (ONH) photographs, and to compare algorithm-produced parameters with manual photogrammetry (MP), scanning laser ophthalmoscope (SLO) and optical coherence tomography (OCT) measurements.

Methods: One hundred twenty-two stereoscopic optic disc photographs (61 subjects) were analyzed. Disc area, rim area, cup area, cup/disc area ratio, vertical cup/disc ratio, rim volume and cup volume were automatically computed by the algorithm. Latent variable measurement error models were used to assess measurement reproducibility for the four techniques.

Results: AP had better reproducibility for disc area and cup volume and worse reproducibility for cup/disc area ratio and vertical cup/disc ratio, when the measurements were compared to the MP, SLO and OCT methods.

Conclusion: AP provides a useful technique for an objective quantitative assessment of 3D ONH structures.

Show MeSH