The Effect of Larger and Blend Zone Ablation on Optical Aberrations in Laser Epithelial Keratomileusis (LASEK)

PURPOSE: The purpose of this study is to investigate the postoperative high order aberration after LASEK and to evaluate the effects of LASEK on high order aberration using larger and blend zone ablation. METHODS: Twenty patients out of 28 patients who received treatment were followed up for 3 months. In each case, one eye received conventional ablation LASEK and the other eye received larger and blend zone ablation LASEK. Preoperative and postoperative RMS (root mean square) of Bille aberration maps measurements were made with WaveScan Wavefront(TM) system (VISX, Santa Clara, U.S.A.). RESULTS: RMS of Bille aberration maps at post operation 1 month and post operation 3 months displayed a statistically significant increase compared with preoperative value. (p<0.05) In post operation 3 month, larger and blend zone ablation LASEK treated eyes displayed a statistically significant lower post operative RMS compared to those of conventional ablation LASEK.(p<0.05) CONCLUSIONS: High order aberrations at post operation 1 month and post operation 3 months increased compared with preoperative value. High order aberration after LASEK with larger and blend zone ablation are less pronounced compared to those associated with conventional ablation LASEK. By using larger and blend zone ablation it is possible to minimize the high order aberration of the eye and improve visual results for patients undergoing LASEK.

Comparison of Optical Aberrations and Contrast Sensitivity between Monofocal and Multifocal Intraocular Lens

PURPOSE: The purpose of this study was to compare the postoperative contrast sensitivity and optical aberration between monofocal and multifocal IOL implanted patients. METHODS: Postoperative contrast sensitivity and optical aberration were measured for 7 cataract patients, 12 eyes that underwent monofocal IOL implantation and for 8 cataract patients, 9 eyes that underwent multifocal IOL implantation. Phacoemulsification was conducted on all patients prior to either multifocal or monofocal IOL implantation, and Multivison Contrast Tester (MCT 8000, Vistech, Dayton, U.S.A.) and WaveScan WavefrontT M system (VISX, Santa Clara, U.S.A.) were used to measure contrast sensitivity and optical aberration. RESULTS: Under the nighttime contrast sensitivity mode, the multifocal-group displayed a statistically significant decrease in contrast sensitivity compared to the monofocal-group (P< 0.01), while there was no statistical difference in the optical aberration index of the two groups. (the multi-group; 0.36, the monogroup; 0.31, p=0.64) CONCLUSIONS: After cataract extraction, there was no difference in the optical aberration between the multifocal IOL implantated patients and the monofocal IOL implanted patients. The decrease in postoperative contrast sensitivity was subjectively greater for multifocal IOL implantated patients than the monofocal IOL implanted patients.