Posters

Effects of laser in situ keratomileusis (LASIK) on corneal biomechanical measurements with the Corvis ST tonometer

Poster Details

First Author: A.Frings GERMANY

Co Author(s):    E. Bauer   J. Steinberg   M. Casagrande   V. Druchkiv   T. Katz   S. Linke

Abstract Details

Purpose:

This study was initiated to evaluate corneal biomechanical parameters using a Corvis ST tonometer (CST), and to investigate whether laser in situ keratomileusis (LASIK) had an impact on CST data. We investigated the dynamic reaction of the cornea to an air impulse to quantify the viscoelastic properties of the cornea.

Setting:

University Medical Centre Hamburg-Eppendorf, Germany.

Methods:

This retrospective study included 64 eyes of 38 refractive patients. All CST measurements were performed 1 day before surgery and at the 1-month follow-up examination. The LASIK procedure included mechanical flap preparation using a Moria SBK microkeratome and an Allegretto excimer laser platform. We applied the latest CST software update released in December 2013.

Results:

Statistically significant differences were observed for mean 2nd applanation length, mean 1st and 2nd deflection lengths, mean 1st and 2nd deflection amplitudes, radius and radius of curvature. Significant positive correlations were found between the change (Δ) in manifest refraction spherical equivalent (MRSE) and the Δradius of curvature, between the ablation depth and Δradius of curvature, and between the Δintraocular pressure and Δradius of curvature. Each diopter of myopic correction in MRSE resulted in an increase in Δradius of curvature of 0.2 mm.

Conclusions:

CST and its parameters are useful for describing the deformation response of healthy and post-LASIK cornea. We found that several parameters were statistically significantly altered by LASIK. This indicates that flap creation, ablation, or both, significantly change the ability of the cornea to absorb or dissipate energy. FINANCIAL INTEREST: NONE