[Corneal biomechanics: Corvis® ST parameters after LASIK]

Corneal refractive surgery alters the biomechanical properties of the cornea.

This study was initiated to evaluate corneal biomechanical parameters after LASIK using a Corvis® ST tonometer (CST).

This retrospective study included 51 eyes of 32 myopic 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.

Statistically significant differences were observed for mean second applanation length, mean first and second deflection lengths, mean first and second deflection amplitudes, peak distance and radius of curvature. Statistically significant positive correlations were found between the change (Δ) in radius of curvature and Δ in manifest refraction spherical equivalent (MRSE), between the ablation depth and the Δ in intraocular pressure. Applying multiple regression models also revealed statistically significant differences in parameters obtained by CST measurements.

Several CST parameters were statistically significantly altered by LASIK thereby indicating that flap creation, ablation or both, significantly change the ability of the cornea to absorb or dissipate energy.