Posters

Comparison of higher order aberration induction between Hansatome microkeratome and VisuMax femtosecond laser flap creation

Poster Details

First Author: C.Yvon UK

Co Author(s):    D. Reinstein   T. Archer   M. Gobbe        

Abstract Details

Purpose:

To compare the change in aberrations produced by the Hansatome microkeratome (Bausch & Lomb) and VisuMax femtosecond laser (Carl Zeiss Meditec) and correlate these to hinge position and flap thickness profile regularity.

Setting:

London Vision Clinic, London, UK

Methods:

In a retrospective consecutive series of 62 eyes, corneal and whole eye wavefront data were collected before and after flap creation using Hansatome microkeratome and VisuMax femtosecond laser. The 2 groups had analogous enrolment criteria and were operated on under similar circumstances by the same surgeon. To minimise any aberration induction effect due to stromal tissue removal, only emmetropic presbyopic patients receiving minimal laser ablation (+0.125 to +0.50 D spherical equivalent) were included. Changes in root mean square (RMS) and individual higher order aberrations (HOAs) were compared between Hansatome and VisuMax using both whole-eye Hartmann-Shack aberrometry (WASCA, Wavefront Aberration Supported Cornea Ablation) and corneal front surface aberrometry (ATLAS placido topography system).

Results:

Hansatome flap creation produced whole eye and corneal aberration changes in trefoil and horizontal coma (both p<0.001). VisuMax flap creation produced whole eye aberrometry (but oddly not corneal aberrometry) changes in horizontal coma (p<0.001) and in vertical coma (p=0.047). Both mechanical and femtosecond groups demonstrated a small change in spherical aberration (p<0.001), although this was as expected by the refractive ablations.

Conclusions:

There was greater induction of horizontal coma and trefoil aberrations with the Hansatome microkeratome than the VisuMax femtosecond laser. Orientation of the coma induced was not found to be correlated to hinge position. The overall pattern of coma and trefoil aberrations induced by the Hansatome correlated highly with the thickness profile pattern of Hansatome flap thickness, suggesting that aberration induction is related to flap thickness regularity and the relative irregular biomechanical effect thereof. FINANCIAL INTEREST: One of more of the authors... has significant investment interest in a company producing, developing or supplying product or procedure presented, One of more of the authors... receives consulting fees, retainer, or contract payments from a company producing, developing or supplying the product or procedure presented