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Biomedical Optics Express

Biomedical Optics Express

  • Editor: Joseph A. Izatt
  • Vol. 3, Iss. 5 — May. 1, 2012
  • pp: 814–824

Quantitative OCT-based corneal topography in keratoconus with intracorneal ring segments

Sergio Ortiz, Pablo Pérez-Merino, Nicolas Alejandre, E. Gambra, I. Jimenez-Alfaro, and Susana Marcos  »View Author Affiliations

Biomedical Optics Express, Vol. 3, Issue 5, pp. 814-824 (2012)

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Video Abstract

Quantitative OCT-based corneal topography in keratoconus with intracorneal ring segments


Custom high-resolution high-speed anterior segment spectral domain Optical Coherence Tomography (OCT) was used to characterize three-dimensionally (3-D) corneal topography in keratoconus before and after implantation of intracorneal ring segments (ICRS). Previously described acquisition protocols were followed to minimize the impact of the motions of the eye. The collected set of images was corrected from distortions: fan (scanning) and optical (refraction). Custom algorithms were developed for automatic detection and classification of volumes in the anterior segment of the eye, in particular for the detection and classification of the implanted ICRS. Surfaces were automatically detected for quantitative analysis of the corneal elevation maps (fitted by biconicoids and Zernike polynomials) and pachymetry. Automatic tools were developed for the estimation of the 3-D positioning of the ICRS. The pupil center reference was estimated from the segmented iris volume. The developed algorithms are illustrated in a keratoconic eye (grade III) pre- and 30 days post-operatively after implantation of two triangular-section, 0.3-mm thick Ferrara ring segments. Quantitative corneal topographies reveal that the ICRS produced a flattening of the anterior surface, a steepening of the posterior surface, meridional differences in the changes in curvature and asphericity, and increased symmetry of the anterior topography. Optical distortion correction through the ICRS (of a different refractive index from the cornea) allowed accurate pachymetric estimates, which showed increased thickness in the ectatic area as well as in peripheral corneal areas. Automatic tools allowed estimation of the depth of the implanted ICRS ring, as well as its rotation with respect to the pupil plane. Anterior segment sOCT provided with fan and optical distortion correction and analysis tools is an excellent instrument for evaluating and monitoring keratoconic eyes and for the quantification of the changes produced by ICRS treatment.

© 2012 OSA

OCIS Codes
(110.4500) Imaging systems : Optical coherence tomography
(110.6880) Imaging systems : Three-dimensional image acquisition
(120.4640) Instrumentation, measurement, and metrology : Optical instruments
(120.6650) Instrumentation, measurement, and metrology : Surface measurements, figure
(330.7327) Vision, color, and visual optics : Visual optics, ophthalmic instrumentation

ToC Category:
Ophthalmology Applications

Original Manuscript: February 14, 2012
Revised Manuscript: March 16, 2012
Manuscript Accepted: March 21, 2012
Published: April 2, 2012

Sergio Ortiz, Pablo Pérez-Merino, Nicolas Alejandre, E. Gambra, I. Jimenez-Alfaro, and Susana Marcos, "Quantitative OCT-based corneal topography in keratoconus with intracorneal ring segments," Biomed. Opt. Express 3, 814-824 (2012)

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