April 2014
Volume 55, Issue 13
ARVO Annual Meeting Abstract  |   April 2014
The Effect of Corneal Collagen Crosslinking on Stromal Transport, Electrical, and Mechanical Properties
Author Affiliations & Notes
  • R Glenn Hepfer
    Bioengineering, Clemson University, Charleston, SC
  • Changcheng Shi
    Bioengineering, Clemson University, Charleston, SC
  • George O Waring
    Bioengineering, Clemson University, Charleston, SC
    Ophthalmology, Medical University of South Carolina, Charleston, SC
  • Hai Yao
    Bioengineering, Clemson University, Charleston, SC
  • Footnotes
    Commercial Relationships R Glenn Hepfer, None; Changcheng Shi, None; George O Waring, None; Hai Yao, None
  • Footnotes
    Support None
Investigative Ophthalmology & Visual Science April 2014, Vol.55, 2989. doi:
  • Views
  • Share
  • Tools
    • Alerts
      This feature is available to authenticated users only.
      Sign In or Create an Account ×
    • Get Citation

      R Glenn Hepfer, Changcheng Shi, George O Waring, Hai Yao; The Effect of Corneal Collagen Crosslinking on Stromal Transport, Electrical, and Mechanical Properties. Invest. Ophthalmol. Vis. Sci. 2014;55(13):2989.

      Download citation file:

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

  • Supplements

Purpose: This study investigates the effect of crosslinking (CXL) on transport, electrical, and mechanical properties of the stroma. We hypothesize that regional changes in transport properties, observed with fluorescence recovery after photobleaching (FRAP), will be a sensitive measurement of crosslinking effect. We predict that conductivity and compression tests will detect changes in electrical and mechanical properties due to CXL.

Methods: Standard, epithelium-off corneal CXL was performed on fresh, intact porcine eyes while controls received riboflavin without irradiation. FRAP was performed at different stromal depths, and nasal-temporal (X) and superior-inferior (Y) diffusivities were calculated with a custom program. To evaluate the effect of crosslinking on diffusivity in the anterior-posterior (Z) direction, an electrical method was employed to calculate overall conductivity, dependent on small ion diffusivity. For confined compression tests, an additional untreated control group was added. Swelling pressure of buttons were measured in saline followed by a creep test to calculate hydraulic permeability and aggregate modulus using the biphasic theory. Dynamic tests measured the storage and loss modulus.

Results: Normalized XY diffusivities of crosslinked and control porcine corneas were significantly increased (P=0.005, ANOVA) in the anterior cornea. This difference decreased as stromal depth increased (R=-0.87, Pearson’s). However, in the Z direction, conductivity decreased (P<0.0001, ANOVA) in porcine corneas, indicating a corresponding decrease in diffusivity in the Z-direction. Aggregate modulus increased with CXL while this increase was not statistically significant. Hydraulic permeability decreased and swelling pressure increased in both CXL and riboflavin groups when compared to untreated. Storage and loss modulus both increased in CXL when compared to riboflavin and untreated groups.

Conclusions: The effect of CXL is more pronounced in the anterior stroma. We present a non-destructive ex vivo method for quantifying and comparing crosslinking effect with respect to stromal depth. The observed anisotropic change in diffusivity has implications for the CXL mechanism. The changes detected by static confined compression tests were due to effects of the dextran in the riboflavin solution while those detected by dynamic tests were due to crosslinking.

Keywords: 574 keratoconus • 480 cornea: basic science • 484 cornea: stroma and keratocytes  

This PDF is available to Subscribers Only

Sign in or purchase a subscription to access this content. ×

You must be signed into an individual account to use this feature.