Abstract
Abstract: :
Purpose: to evaluate the predictability, effectiveness, safety, tissue ablation depth in LASIK for high myopia. Further, we screened all topographic data for manifest corneal ectasia. Methods: 55 eyes (32 patients) treated with LASIK for an attempted mean spherical equivalent correction of –13.2 diopters (D) +/- 2.3 (SD) (range –10.0 to –23.8 D) were evaluated. Mean follow–up was 42.4 months +/- 17.5 (SD) (range 9.6 to 72.1). All topographic maps were screened for steepening of the central optical zone. Results: 25 eyes (45.5 %) were within +/- 1 D of the planned spherical equivalent correction, whereas 43 eyes (78.2 %) were within +/- 2 D of the planned correction. The safety index (using Snellen preoperative and postoperative BCVA) was 0,983. The efficacy index (using Snellen preoperative BCVA and postoperative BUVA) was 0,562. Mean ablation zone diameter ( Keracor 116 multizone software program ) was 5,8 mm +/- 0,57 (SD) (range 4,4 to 7,0). Mean programmed laser ablation was 142.1 microns +/- 23.1 (SD) (range 97.0 to 188.0 microns) Mean achieved laser ablation, calculated as the difference between preoperative and postoperative pachymetry was 93.9 microns +/- 26.5 (SD) (range 37.0 to 163 microns). Mean remaining stromal bed, calculated as the difference between postoperative pachymetry and used baseplate was 302.7 microns +/- 3.7 (SD) (range 236 to 373 microns). Conclusion: In this study, LASIK seemed to be effective and safe in the correction of high myopia. After LASIK, the change in corneal thickness averages 48.2 microns +/- 20.2 (SD) (range 6 to 90 microns) less than expected. Even in the cases where the remaining stromal bed was less than 250 microns, no case of corneal ectasia was detected.
Keywords: refractive surgery: LASIK • refractive surgery: complications • myopia