June 2023
Volume 64, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2023
Keratoconus corneas deform more than normal corneas in response to the ocular pulse
Jun Liu; Sunny Kwok; Xueliang Pan; Andrew Hendershot
Author Affiliations & Notes
  • Jun Liu
    Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio, United States
    Department of Ophthalmology and Visual Sciences, The Ohio State University, Columbus, Ohio, United States
  • Sunny Kwok
    Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio, United States
  • Xueliang Pan
    Department of Biomedical Informatics, The Ohio State University, Columbus, Ohio, United States
  • Andrew Hendershot
    Department of Ophthalmology and Visual Sciences, The Ohio State University, Columbus, Ohio, United States
  • Footnotes
    Commercial Relationships   Jun Liu None; Sunny Kwok None; Xueliang Pan None; Andrew Hendershot None
  • Footnotes
    Support  NIHR01EY025358
Investigative Ophthalmology & Visual Science June 2023, Vol.64, 1691. doi:
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      Jun Liu, Sunny Kwok, Xueliang Pan, Andrew Hendershot; Keratoconus corneas deform more than normal corneas in response to the ocular pulse. Invest. Ophthalmol. Vis. Sci. 2023;64(8):1691.

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Abstract

Purpose : We have developed a high-resolution ultrasound elastography method to measure corneal deformation induced by the ocular pulse. In this study we compared corneal axial strains (CAS) in keratoconus (KC) patients and normal controls. We also qualitatively evaluated the spatial mapping of CAS in some KC corneas.

Methods : Twenty normal controls (40 eyes) and 20 KC patients (35 eyes) were recruited. Each subject underwent three tests: (1) OCULUS Pentacam for corneal topography; (2) PASCAL Dynamic Contour Tonometry for intraocular pressure (IOP) and ocular pulse amplitude (OPA), and (3) ocular pulse elastography (OPE) for corneal displacements and strains using the Vevo2100 ultrasound system. Corneal topography data was reviewed by a specialist (AH) to determine the presence and grade of KC. Each eye underwent 4 ultrasound measurements, each acquiring 1000 frames in 8 secs of the cornea during fixation. This data was processed to obtain corneal displacements and CAS following our published protocols [Kwok et al, PLoS ONE 17(7):e0271749]. Corneal stiffness was calculated as OPA/CAS for each eye. Linear mixed models for repeated measures were used to account for association between two eyes of the same subject in data analysis.

Results : Mean CAS magnitude (in %) was significantly higher (p=0.032, Fig. 1A) in KC (0.169, 95% CI: 0.061, 0.278) than normal (0.050, 95% CI: 0.038, 0.061). Mean corneal stiffness (unit: mmHg/%) was significantly lower (p=0.001, Fig. 1B) in KC (33.7, 95% CI: 22.1, 44.3) than normal (115.1, 95% CI: 70.8, 159.3). Age, IOP, and OPA were not statistically different between groups. High strains were observed in the cone region of KC corneas of different grade (Fig. 2).

Conclusions : KC corneas deformed more (i.e., larger CAS) than normal corneas in response to the ocular pulse, confirming biomechanical weakening in KC. High strains appeared to concentrate in the cone region, indicating that the cone may have the greatest mechanical weakening. Ultrasound elastography may provide both quantitative and spatially resolved biomechanical evaluation of the cornea to aid in KC diagnosis.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.

 

Fig. 1: A. CAS was significantly higher in KC than normal. B. Corneal stiffness was significantly lower in KC than normal. A few ouliers were outside the range and not shown.
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Fig. 1: A. CAS was significantly higher in KC than normal. B. Corneal stiffness was significantly lower in KC than normal. A few ouliers were outside the range and not shown.

Fig. 1: A. CAS was significantly higher in KC than normal. B. Corneal stiffness was significantly lower in KC than normal. A few ouliers were outside the range and not shown.

Fig. 1: A. CAS was significantly higher in KC than normal. B. Corneal stiffness was significantly lower in KC than normal. A few ouliers were outside the range and not shown.
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Fig. 2: The cone region (area between two dashed lines) had higher strains (dark red in CAS map overlaid on ultrasound image) in three KC corneas.
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Fig. 2: The cone region (area between two dashed lines) had higher strains (dark red in CAS map overlaid on ultrasound image) in three KC corneas.

Fig. 2: The cone region (area between two dashed lines) had higher strains (dark red in CAS map overlaid on ultrasound image) in three KC corneas.

Fig. 2: The cone region (area between two dashed lines) had higher strains (dark red in CAS map overlaid on ultrasound image) in three KC corneas.
View OriginalDownload Slide

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.
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Copyright © 2024 Association for Research in Vision and Ophthalmology.
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