June 2013
Volume 54, Issue 15
Free
ARVO Annual Meeting Abstract  |   June 2013
Automatic Segmentation of Corneal Lamellar Graft Surfaces from Low-Contrast Optical Coherence Tomography Images
Author Affiliations & Notes
  • Alec Arshavsky
    East Chapel Hill High School, Chapel Hill, NC
    Ophthalmology, Duke University, Durham, NC
  • Francesco LaRocca
    Biomedical Engineering, Duke University, Durham, NC
  • Joseph Izatt
    Biomedical Engineering, Duke University, Durham, NC
    Ophthalmology, Duke University, Durham, NC
  • Anthony Kuo
    Ophthalmology, Duke University, Durham, NC
  • Sina Farsiu
    Biomedical Engineering, Duke University, Durham, NC
    Ophthalmology, Duke University, Durham, NC
  • Footnotes
    Commercial Relationships Alec Arshavsky, None; Francesco LaRocca, None; Joseph Izatt, Bioptigen, Inc. (I), Bioptigen, Inc. (P), Bioptigen, Inc. (S); Anthony Kuo, Bioptigen (P); Sina Farsiu, Duke University (P)
  • Footnotes
    Support None
Investigative Ophthalmology & Visual Science June 2013, Vol.54, 5530. doi:
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    • Get Citation

      Alec Arshavsky, Francesco LaRocca, Joseph Izatt, Anthony Kuo, Sina Farsiu; Automatic Segmentation of Corneal Lamellar Graft Surfaces from Low-Contrast Optical Coherence Tomography Images. Invest. Ophthalmol. Vis. Sci. 2013;54(15):5530.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract
 
Purpose
 

Endothelial keratoplasty (EK) is a widely used form of corneal transplantation for corneal endothelial disease. By using OCT to examine cut donor tissue for EK, characterization of the lamellar cut is possible. We present methods to automatically identify the intrastromal lamellar dissection (ILD) and the endothelial surfaces of precut donor tissue. We previously developed an algorithm for segmentation of corneal layers in normal eyes (LaRocca, et al. BOE, 2011). However, the quality of many OCT images from donor tissue in storage is exceptionally low (Fig 1). Moreover, LaRocca’s algorithm was not designed to identify the ILD surface. Thus, in this work, we developed a dedicated algorithm for these low-quality images.

 
Methods
 

We introduce a novel, more robust implementation of our graph theory and dynamic programming (GTDP) segmentation framework. We first attain a pilot estimate of the target surfaces by classic GTDP. Next, we find erroneously segmented surfaces based on morphologic a priori assumptions about grafts and iteratively refine the reliable fragments of each segmented surface. We achieve the final estimate of the surfaces by finding the shortest path from a graph of these reliable fragments. We tested our new algorithm on a total of 250 B-scans (each of size 512×1000) from 5 donor eyes. An expert corneal surgeon evaluated and reported the percentage of correctly segmented surfaces not requiring manual correction. The proportion of correctly segmented surfaces between the new and previous LaRocca algorithm was compared using Fisher’s exact test.

 
Results
 

Our new automatic algorithm correctly segmented the ILD in 83.6% of images compared to 4.8% by the LaRocca algorithm (p<0.0001). Our new automatic algorithm correctly segmented the endothelial layer in 66.0% of images compared to 0.0% by the LaRocca algorithm (p<0.0001).

 
Conclusions
 

The new automatic algorithm accurately segmented the ILD and the endothelial surfaces in the majority of OCT images from donor corneas and was significantly better than the prior algorithm. This robust automated approach may significantly reduce the resources and time necessary to conduct large-scale screening of precut corneal donor tissue.

 
 
Fig.1: A) Low-quality corneal image. B) Automatic segmented image by our new method. The solid (green) line corresponds to the ILD, and the dashed (red) line corresponds to the endothelial surface.
 
Fig.1: A) Low-quality corneal image. B) Automatic segmented image by our new method. The solid (green) line corresponds to the ILD, and the dashed (red) line corresponds to the endothelial surface.
 
Keywords: 549 image processing • 550 imaging/image analysis: clinical • 481 cornea: endothelium  
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