Abstract

SA.27.01

Hysteresis change after femtosecond lasik in myopic eyes

Derhartunian V.¹, Kohnen T.^1,2
1Klinik für Augenheilkunde, Johann Wolfgang Goethe-Universität, Frankfurt am Main; ²Cullen Eye Institute, Baylor College of Medicine, Houston, USA

Objective: The Ocular Response Analyzer (Reichert) is a new device that measures corneal biomechanical properties. A rapid air jet from the device temporarily deforms the corneal surface. The inward (P1) and outward (P2) air pressure leads to a state of applanation of the cornea. The difference in P2-P1 defines hysteresis (in mmHg). The aim of this study is to compare the hysteresis before and after femto lasik in myopic eyes.
Methods: Twenty eyes of ten patients for the correction of myopia and myopic astigmatism underwent femto lasik. Corneal flap creation was performed with the FS60 Femtosecond laser (Intralase), corneal excimer laser ablation with the Technolas 217Z 100 Hz (Bausch&Lomb). Corneal hysteresis and the corneal resistance factor (CRF) was determined before and after the operation.
Results: The mean age of patients was 36.59±7.53 years. Mean preoperative values were as follows: spherical equivalent -4.80±1.43 diopters(D), pachymetry 556.55±33.93µm, corneal ablation 89.35±23.24µm, hysteresis 11.08±1.03 mmHg, CRF 11.24±1.23 mmHg. Mean postoperative values were: spherical equivalent -0.29±0.49 D, hysteresis 8.50±1.15 mmHg, CRF 7.56±1.60mmHg. The mean postoperative observation time was 19.40±11.26 days. We found highly statistically significant differences (p=0.000002) between pre- and postoperatively measured hysteresis.
Conclusions: After the correction of myopia with the femtosecond lasik, there is a change in biomechanical properties of the cornea. These changes can be quantified with the Ocular Response Analyzer.

Copyright: Porstmann Kongresse GmbH. All rights reserved. Impressum, Disclaimer.