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104. Jahrestagung der Deutschen Ophthalmologischen Gesellschaft 2006
Abstract
Abstract
FR.06.06 Assessment of cyclorotation of the eye during wavefront-guided LASIK with iris recognition Kohnen T., Strenger A., Cichocki M., Kühne C.
Johann Wolfgang Goethe University Frankfurt, Department of Ophthalmology Objective: Centration and rotational symmetry of the ablation zone decisively influence the result of the laser treatment. Cyclorotation of the eye occurs as the patient changes from sitting position during aberrometry to supine position during laser surgery. If not compensated, cyclorotation may lead to shifting of the ablation zone and thus make induction of higher-order aberrations more likely.
Methods: 20 patients/ 40 eyes received wavefront-guided laser treatment with iris tracker (ZyoptixTM Version 5.09, B&L) for the correction of myopia and myopic astigmatism. Mean preoperative spherical equivalent (SE) was -4.72±1.45 D (range -1.63 to -7.00 D). The iris patterns of the patients' eyes were memorised (Zywave, Software Version 3.21, B&L/Technolas) while the patient was sitting during measurement of the wavefront error (aberrometry). Prior to LASIK treatment, an active eye tracking system with iris recognition scanned the structure of the iris once more. While this is done, the eye tracker compares the eye's position with the position the eye had preoperatively as the patient was sitting, and compensates occurring torsion movements.
Results: Mean cyclorotation was 3.5±2.7º (range 0.1 to 11.0º). In 65% of all eyes (n=26) cyclorotation was >2º. Mean values for right and left eyes separately are 3.3±2.7º (OD) and 3.6±2.8º (OS). During change from sitting to supine position, 70% or all right eyes performed incyclorotation, 70% of all left eyes performed excyclorotation.
Conclusions: Use of active eye tracker systems with iris recognition make it possible to enhance exactness of positioning the ablation profile as they detect and compensate cyclorotation. This helps reduce induction of higher order aberrations and improve optical quality after refractive surgical treatments.
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