Changes to corneal biomechanics introduced by topographic cross-linking evaluated by speckle interferometry

Session Details

Session Title: Cross-Linking

Session Date/Time: Tuesday 25/09/2018 | 14:00-16:00

Paper Time: 14:52

Venue: Room A3, Podium 3

First Author: : A.Wilson UK

Co Author(s): :                        

Abstract Details

Purpose:

Experiments were conducted to determine the effectiveness of laser speckle interferometry techniques for the assessment of corneal biomechanics and the changes to the regional response that could be introduced by crosslinking in specific topographic regions in isolation.

Setting:

Wolfson School of Mechanical, Manufacturing and Electrical Engineering, Loughborough University, Loughborough, UK

Methods:

Electronic Speckle Pattern Interferometry (ESPI) and Lateral Shearing Interferometry (LSI) were used to measure the surface deformation of 6 human corneal-scleral buttons in response to hydrostatic pressure variations equivalent in magnitude to those that occur during the ocular pulse cycle. The response was examined after epithelium removal and then after soaking in riboflavin (VibeX-Xtra, Avedro Inc.) for 8 minutes and exposing to a UVA source (KXL, Avedro Inc.) for 8 minutes at a power of 15 mW/cm2 in specific topographic locations only (central 3 mm circle, 9 mm doughnut, central 3 mm vertical strip and central 3 mm horizontal strip).

Results:

Corneal surface deformation was quantified across the full corneal surface with a sensitivity greater than 0.2 µm. All corneas demonstrated significant regional variations in biomechanics prior to crosslinking. Post-crosslinking the distribution of the corneal response to a given pressure increase changed significantly, with a decrease in the magnitude of displacement of between 16% to 80% dependent upon the location of the crosslinked region.

Conclusions:

ESPI and LSI are effective tools for analysing full-field corneal surface deformation in response to physiological-scale pressure variations and are capable of detecting the regional biomechanical changes introduced by crosslinking. Due to the significant regional variability in the biomechanical response of the cornea it is necessary to quantify these properties to enable the regionally specific effects of topographic crosslinking to be determined so its application can be tailored to achieve optimal refractive outcomes.

Financial Disclosure:

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