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Robust Estimation of Corneal Limbus From the Placido-Disk Videokeratoscopic Images

Iskander, D. Robert, Morelande, Mark R., Collins, Micahel J., Franklin, Ross J., & Davis, Brett A. (2003) Robust Estimation of Corneal Limbus From the Placido-Disk Videokeratoscopic Images. Investigative Ophthalmology and Visual Science, 44, p. 3673.

Abstract

Purpose: Accurate knowledge of the corneal limbus is important when calculating corneal surface area, finding the corneal centroid and comparing it to the pupil centre or corneal apex. Existing techniques for estimating corneal limbus from digital photographs are based on manual measurements or computer based image processing. We aim to develope a robust and accurate technique that can be applied to videokeratoscope images routinely acquired during corneal topography measurements. Methods: We have refined our recently reported soft edge detection method [IEEE Transactions on Biomedical Engineering, 49(12), 2002] to a scheme in which the estimation of the corneal limbus from a placido-disk videokeratoscopic images is performed in a more accurate manner. This has been achieved with the help of a bootstrap technique that calculates the bias of the corneal limbus estimator. Results: Corneal limbus estimation was performed on 16 subjects (32 eyes) from a variety of ethnic backgrounds. The refined technique for estimating corneal limbus that includes the bootstrap estimation step showed better accuracy (<50 microns) when compared to the previous method. The accuracy is relative to a manual computer aided technique in which an experienced operator selects points in an image that lie on the limbus. Conclusions: The proposed algorithm for estimating corneal limbus can add important clinical value to the output of the placido disk videokeratoscopes. The technique can also be used for robust estimation of the pupil diameter.

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ID Code: 12139
Item Type: Journal Article
Additional Information: For more information, please refer to the journal’s website (see hypertext link) or contact the author.
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Keywords: imaging/image analysis, clinical • topography • refractive surgery, corneal topography
ISSN: 0146-0404
Subjects: Australian and New Zealand Standard Research Classification > MEDICAL AND HEALTH SCIENCES (110000) > OPTOMETRY AND OPHTHALMOLOGY (111300)
Australian and New Zealand Standard Research Classification > MEDICAL AND HEALTH SCIENCES (110000) > OPTOMETRY AND OPHTHALMOLOGY (111300) > Vision Science (111303)
Australian and New Zealand Standard Research Classification > MEDICAL AND HEALTH SCIENCES (110000) > OPTOMETRY AND OPHTHALMOLOGY (111300) > Optical Technology (111302)
Divisions: Current > Research Centres > Centre for Health Research
Current > QUT Faculties and Divisions > Faculty of Health
Current > Institutes > Institute of Health and Biomedical Innovation
Copyright Owner: Copyright 2003 Association for Research in Vision and Ophthalmology
Deposited On: 21 Jan 2008
Last Modified: 11 Aug 2011 00:09

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