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Proceedings Paper

Reproducibility study of placido-based corneal topography systems
Author(s): Ronald R. Krueger; Roddy Frankel; Kerry K. Assil; David J. Schanzlin; Medhat F. Guirgis
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Paper Abstract

We have developed a computer software program that analyzes the reproducibility of corneal topography systems. Using a Macintosh computer with Microsoft QuickBasic programming we created a program that records and analyzes the corneal power of 72,000 points per topography map (200 points over each one degree meridian) by linear interpolation of the Placido-based ring data. Reproducibility studies on 7 normal and 7 abnormal (pathological and postsurgical) corneas were performed with 2 Placido ring based topography systems with EyeSys Corneal Analysis System and the Humphrey MasterView system. Five exams were performed by two technicians each. The mean, range and standard deviation of corneal power was calculated for all points on a map, and represented pictorially for each patient. Statistical analysis of standard deviation at each point was used in assessing the reproducibility between systems and between technicians. The topographic maps of mean power range and standard deviation are presented for selected patients. The overall mean standard deviation of power and the means within concentric annular zones and quadrants are presented for each system and technician for both normal and abnormal cornea. Intraobserver variability of each system were not significantly different for both normal and abnormal corneas. There was no significant difference between technicians, nor were there regional differences in variability.standard deviation of power is presented for each system and technician comparing intersystem and intraobserver variability for both normal and abnormal corneas. A precise method of analyzing multiple variation of reproducibility in corneal topography is now available through a new proprietary software system.

Paper Details

Date Published: 22 May 1995
PDF: 8 pages
Proc. SPIE 2393, Ophthalmic Technologies V, (22 May 1995); doi: 10.1117/12.209825
Show Author Affiliations
Ronald R. Krueger, Anheuser-Busch Eye Institute/St. Louis Univ. (United States)
Roddy Frankel, Anheuser-Busch Eye Institute/St. Louis Univ. (United States)
Kerry K. Assil, Anheuser-Busch Eye Institute/St. Louis Univ. (United States)
David J. Schanzlin, Anheuser-Busch Eye Institute/St. Louis Univ. (United States)
Medhat F. Guirgis, New Jersey Medical School (United States)

Published in SPIE Proceedings Vol. 2393:
Ophthalmic Technologies V
Jean-Marie Parel; Qiushi Ren; Karen Margaret Joos, Editor(s)

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