July 2018
Volume 59, Issue 9
Open Access
ARVO Annual Meeting Abstract  |   July 2018
Differences in Corneal Biomechanical Behavior between Normal and Keratoconic Corneas using In-vivo Optical Coherence Elastography
Author Affiliations & Notes
  • Vinicius Silbiger De Stefano
    Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, United States
    Federal University of Sao Paulo, Sao Paulo, SP, Brazil
  • Matthew R Ford
    Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, United States
  • Ibrahim Seven
    Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, United States
  • Brent Hughes
    OptoQuest, Inc., Cleveand, Ohio, United States
  • William J Dupps
    Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, United States
    Dept. of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, United States
  • Footnotes
    Commercial Relationships   Vinicius De Stefano, None; Matthew Ford, OptoQuest (P); Ibrahim Seven, OptoQuest (C); Brent Hughes, OptoQuest (E); William Dupps, OptoQuest (P)
  • Footnotes
    Support  NIH R01 EY023381; An Unrestricted Grant Awd from Research to Prevent Blindness to the Department of Ophthalmology, Cole Eye Institute (RPB1508DM); Foundation Fighting Blindness Center Grant to the Cole Eye Institute (CCMM08120584CCF); NEI/NIH P30 Core Center Grant (IP30EY025585); Ohio Third Frontier Commission award TECH 13-059.
Investigative Ophthalmology & Visual Science July 2018, Vol.59, 1386. doi:
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      Vinicius Silbiger De Stefano, Matthew R Ford, Ibrahim Seven, Brent Hughes, William J Dupps; Differences in Corneal Biomechanical Behavior between Normal and Keratoconic Corneas using In-vivo Optical Coherence Elastography. Invest. Ophthalmol. Vis. Sci. 2018;59(9):1386.

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

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Abstract

Purpose : To compare spatially resolved corneal biomechanical properties in normal and keratoconic corneas (KC) of human subjects using optical coherence elastography (OCE).

Methods : A previously described OCE technique (Ford et al, JBO 2011) was implemented in a clinical prototype. The study was approved by the IRB and informed consent was obtained. Corneal displacement was achieved using a flat lens attached to a linear actuator with rapid sampling rate force transducers. A cross-correlation algorithm was applied to track frame-by-frame intrastromal speckle motion. Regional displacements for the anterior and posterior stroma were plotted in a force vs. displacement graph. A displacement/force relationship was defined by dividing the 1st order term of a linear fit of the slope for the anterior (Na) and posterior cornea (Np) so that K=Na/Np. Elastographic maps were generated based on the regional displacement/force variable in each region of the corneal stroma. K values were compared using the Mann-Whitney U test.

Results : Twenty-three eyes were analyzed overall: 14 eyes from 8 normal patients and 9 KC from 7 patients. The overall intraclass correlation was 0.91 (95% CI: 0.77-0.96), indicating good test-retest reliability. The mean K for the normal eyes group was 1.129 ± 0.067 and for the KC group was 0.988 ± 0.089 (p < 0.01). This data is presented in more detail in Table 1, along with tomographic variables for each patient. Figure 1 shows a Pentacam scan, an elastography map and the force vs. displacement graph for one normal and one KC patient.

Conclusions : OCE revealed stiffer behavior in the anterior stroma than in the posterior stroma in normal in vivo corneas. Of note, K values were significantly lower in KC and, on average, were less than 1, indicating a relative loss of native anterior stromal stiffness in the diseased corneas. Several KCs demonstrated an inversion of the normal property gradient. This finding is consistent with histopathological evidence of Bowman-level abnormalities and regional loss of interlacing fibrils in KC. OCE may be a useful tool for detecting early changes in spatial biomechanical properties in a clinical setting

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.

 

Descriptive values for curve fit and relationship between anterior and posterior stroma in normal and keratoconic corneas

Descriptive values for curve fit and relationship between anterior and posterior stroma in normal and keratoconic corneas

 

Elastography maps and force vs. displacement graphs. Left: normal patient. Right: subject with keratoconus.

Elastography maps and force vs. displacement graphs. Left: normal patient. Right: subject with keratoconus.

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