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Proceedings Paper

The impact of horizontal offset of the cornea during corneal specular microscopy
Author(s): Curry Bucht; Per Söderberg; Göran Manneberg
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Paper Abstract

We are developing automated morphometric analysis of the corneal endothelium. Here, the general impact of horizontal offset of the cornea on morphometry was examined. Errors due to perspective during imaging with a Clinical Specular Microscope (CSM) were analyzed considering semi automated analysis software and fully automated Fourier analysis software. Methods: A mathematical model of the cornea was created. Trigonometry was applied to find the relationship between the horizontal offset of the cornea relative to the microscope objective, and the consecutive errors from perspective changes in the image. An experimental setup was created using a cornea made of polymethyl methacrylate (PMMA). The posterior surface of the PMMA cornea was horizontally marked. The PMMA cornea was placed in a holder. Difference in refractive index between real endothelium and aqueous humor was emulated using high refractive index liquid. Images with varying horizontal offset on the PMMA corneal posterior surface, along with their relative offset coordinates were captured, using CSM. Results: Experiments using controlled offset of the cornea in relation to its center estimated that analyzable images can be acquired within an interval of 1.26 mm, using central cornea sampling CSM. Because of refractive indices along with light scattering differences between the corneal tissue and PMMA , the 1.26 mm interval should be considered a first estimate for feasible CSM images. The effect of corneal endothelial offset during imaging with CSM or fully automated Fourier analysis should be considered.

Paper Details

Date Published: 25 February 2008
PDF: 9 pages
Proc. SPIE 6844, Ophthalmic Technologies XVIII, 684413 (25 February 2008); doi: 10.1117/12.779573
Show Author Affiliations
Curry Bucht, St. Erik's Eye Hospital (Sweden)
Stockholm's Royal Institute of Technology (Sweden)
Per Söderberg, St. Erik's Eye Hospital (Sweden)
Univ. of Miami (United States)
Göran Manneberg, Stockholm's Royal Institute of Technology (Sweden)

Published in SPIE Proceedings Vol. 6844:
Ophthalmic Technologies XVIII
Bruce E. Stuck; Michael Belkin; Fabrice Manns; Per G. Söderberg; Arthur Ho, Editor(s)

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