To evaluate the efficacy and safety of laserassisted in situ keratomileusis (LASIK) in patients with preoperative dry eye. Methods: We divided the 543 eyes that underwent LASIK into the following 3 groups: eyes with definite dry eye (DE group), with probable dry eye (PDE group), and without dry eye (NDE group). We evaluated visual outcome, dry-eye status, and complications. Outcome Measures: We compared uncorrected and best-corrected visual acuity, manifest refraction, symptoms, tear function, ocular surface abnormality, complications, corneal sensitivity, endothelial cell count, and patient satisfaction among the groups. Results: We found no significant differences among the groups in uncorrected and best-corrected visual acuity, manifest refraction, and patient satisfaction. A dry-eye symptom, dryness, was more severe in the DE than the NDE group after LASIK. The mean results of the Schirmer test with anesthesia and tear breakup times were significantly lower and the fluorescein score was higher in the DE than the NDE groups after LASIK. We found no differences in the incidence of complications among the groups. Corneal sensitivity was recovered within 6 months after LASIK in the DE and PDE groups and within 3 months in the NDE group. Conclusions: The efficacy and safety of LASIK were not affected by preexisting dry eye. However, preexisting dry eye is a risk factor for severe postoperative dry eye with lower tear function, more vital staining of the ocular surface, and more severe symptoms.
PURPOSE: Positionally induced cyclotorsion could be an important factor in the correction of astigmatism during refractive surgery. We analyzed the change in cyclotorsional rotation during excimer laser ablation in LASIK surgery using the NIDEK Torsion Error Detector (TED).
METHODS: One hundred ten patients (192 eyes) who underwent LASIK for myopic astigmatism, using the NIDEK Advanced Vision Excimer Laser (NAVEX) were measured for cyclotorsion during surgery using the TED system. The manifest refraction of these patients was -6.80?2.74 diopters (D) (range: -1.00 to -13.75 D). The iris pattern of the patient's eyes in the supine position was recorded via a CCD camera in the EC5000CXII excimer laser system, and it was compared to the iris pattern acquired during OPD-Scan measurement in the sitting position.
RESULTS: During laser ablation, the degree of cyclotorsional rotation detected by TED was 1.33 ?1.88 degrees (range: -6.33 to 2.99 degrees) clockwise and 1.00?1.79 degrees (range: -3.70 to 7.34 degrees) counterclockwise. The absolute degree of torsion error detected by the TED system was 2. 33? 1.16 degrees (range: 0 to 6.21 degrees).
CONCLUSIONS: The effectiveness of the cylinder treatment can be reduced due to torsion errors. The degree of cyclotorsion constantly changes during laser ablation. Therefore, a monitoring system should be developed for the measurement of torsion error, and this will enable the maximum possible correction of the error during laser ablation. [J Refract Surg. 2007;23:911-915.]
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