Original articleCorneal Epithelial Thickness Mapping by Fourier-Domain Optical Coherence Tomography in Normal and Keratoconic Eyes
Section snippets
Patients
Subjects of this cross-sectional observational study were recruited at Doheny Eye Institute at the University of Southern California, Los Angeles, California; Brass Eye Center, Latham, New York; Gordon & Weiss Vision Institute, San Diego, California; and the Casey Eye Institute at Oregon Health and Science University, Portland, Oregon. This study followed the tenets of the Declaration of Helsinki and was in accord with the Health Insurance Portability and Accountability Act of 1996. The study
Results
Visual inspection confirmed that anterior corneal and epithelial boundary detection was satisfactory in 432 of 435 normal scans (99.3%) and in 107 of 114 keratoconic scans (93.9%). Three scans of normal eyes and 7 scans of keratoconic eyes were excluded from statistical analysis because of errors in boundary detection. Because the scans with segmentation errors occurred in different normal eyes, neither of those eyes was excluded. The keratoconic boundary detection errors resulted in the loss
Discussion
Fourier-domain OCT instruments can provide scan speeds 10 to 100 times faster than time-domain OCT instruments.26 The enhanced speeds minimize the effect of eye movements during data acquisition and also allow higher definition imaging because of denser axial scans in the same transverse scan length. The higher scan speed also facilitates frame averaging that suppresses speckle noise. The epithelium–Bowman's layer boundary is a relatively weak interface presented in corneal OCT images. In this
Acknowledgment
The authors thank Dr. Qienyuan Zhou for coordinating study data collection, Dr. Xinbo Zhang for consultation in statistics, and Dr. Maolong Tang for consultation on corneal topography.
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Manuscript no. 2011-1777.
Financial Disclosure(s): The author(s) have made the following disclosure(s): Yan Li received travel support, research grant support, patent royalty from Optovue, Inc., Fremont, CA; Ou Tan received research grant support, patent royalty from Optovue, Inc.; Robert Brass receives speaker honoraria from Optovue, Inc.; David Huang received stock options, patent royalty, travel support and research grant support from Optovue, Inc. David Huang receives royalties from the Massachusetts Institute of Technology derived from an optical coherence tomography patent licensed to Carl Zeiss Meditec, Inc. (Dublin, CA).
These potential conflicts of interest have been reviewed and managed by Oregon Health and Science University.
Supported by the National Institutes of Health, Bethesda, Maryland (grant no.: R01EY018184); a research grant from Optovue, Inc., Fremont, California; and an unrestricted grant to Casey Eye Institute from Research to Prevent Blindness, Inc., New York, New York.