Serial biomechanical comparison of edematous, normal, and collagen crosslinked human donor corneas using optical coherence elastography.
OBJECTIVE
To noninvasively evaluate the effects of corneal hydration and collagen crosslinking (CXL) on the mechanical behavior of the cornea.


METHODS
Cleveland Clinic Cole Eye Institute, Cleveland, Ohio, USA.


METHODS
Experimental study.


METHODS
An optical coherence elastography (OCE) technique was used to measure the displacement behavior of 5 pairs of debrided human donor globes in 3 serial states as follows: edematous, normal thickness, and after riboflavin-ultraviolet-A-mediated CXL. During micromotor-controlled axial displacements with a curved goniolens at physiologic intraocular pressure (IOP), serial optical coherence tomography scans were obtained to allow high-resolution intrastromal speckle tracking and displacement measurements over the central 4.0 mm of the cornea.


RESULTS
With no imposed increase in IOP, the mean lateral to imposed axial displacement ratios were 0.035 μm/μm ± 0.037 (SD) in edematous corneas, 0.021 ± 0.02 μm/μm in normal thickness corneas, and 0.014 ± 0.009 μm/μm in post-CXL corneas. The differences were statistically significant (P<.05, analysis of variance) and indicated a 40% increase in lateral stromal resistance with deturgescence and a further 33% mean increase in relative stiffness with CXL.


CONCLUSIONS
Serial perturbations of the corneal hydration state and CXL had significant effects on corneal biomechanical behavior. With an axially applied stress from a nonapplanating contact lens, displacements along the direction of the collagen lamellae were 2 orders of magnitude lower than axial deformations. These experiments show the ability of OCE to quantify clinically relevant mechanical property differences under physiologic conditions.


BACKGROUND
Proprietary or commercial disclosures are listed after the references.
From the Department of Biomedical Engineering (Ford, Rollins), Case Western Reserve University, the Cleveland Clinic Cole Eye Institute (Ford, Sinha Roy, Dupps), and the Department of Biomedical Engineering (Dupps), Cleveland Clinic Lerner Research Institute, Cleveland, Ohio, USA.
Matthew R
MR
Ford
From the Department of Biomedical Engineering (Ford, Rollins), Case Western Reserve University, the Cleveland Clinic Cole Eye Institute (Ford, Sinha Roy, Dupps), and the Department of Biomedical Engineering (Dupps), Cleveland Clinic Lerner Research Institute, Cleveland, Ohio, USA.
Abhijit
A
Sinha Roy
From the Department of Biomedical Engineering (Ford, Rollins), Case Western Reserve University, the Cleveland Clinic Cole Eye Institute (Ford, Sinha Roy, Dupps), and the Department of Biomedical Engineering (Dupps), Cleveland Clinic Lerner Research Institute, Cleveland, Ohio, USA.
Andrew M
AM
Rollins
From the Department of Biomedical Engineering (Ford, Rollins), Case Western Reserve University, the Cleveland Clinic Cole Eye Institute (Ford, Sinha Roy, Dupps), and the Department of Biomedical Engineering (Dupps), Cleveland Clinic Lerner Research Institute, Cleveland, Ohio, USA. Electronic address: bjdupps@sbcglobal.net.
William J
WJ
Dupps
D001696:Biomechanical Phenomena / Q000502:physiology; D003094:Collagen / Q000378:metabolism*; D003315:Cornea / Q000502:physiology*; D015715:Corneal Edema / Q000503:physiopathology*; D003319:Corneal Stroma / Q000378:metabolism / Q000503:physiopathology*; D003432:Cross-Linking Reagents / Q000627:therapeutic use*; D004548:Elasticity / Q000502:physiology*; D054459:Elasticity Imaging Techniques; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology; D014019:Tissue Donors; D041623:Tomography, Optical Coherence
D003432:Cross-Linking Reagents; D003094:Collagen