Comparation Of Higher-order Aberration Changes Between After LASIK With Aggle Kappa Adjusted And After Custom LASIK.

Objective: To investigate the abberation changes of human eyes after LASIK withaggle Kappa adjusted,and compare with the aberration changes of human eyes after custom LASIK.Methods:1. Subjects:Laser in situ keratomileusis(LASIK) were done on 75 patients who was divided into two groups during 2006.12-2007. (1)Experimental group:There were 77 eyes of 39 myopia patients received LASIK with aggle Kappa adjusted.The patients were assigned to three different groups according to the diopter before the surgery.and each group included respectively 24 eyes,27 eyes,26 eyes.All eyes received LASIK by a practised doctor,the doctor adjust the aggies Kappa to 0 during all operations.(2)Normal control group:72 eyes of 36 myopia patients in this group received custom LASIK.They were also assigned to three different groups and operated by the same doctor. Each group included respectively 24 eyes. All the patients were evaluated by the Allegretto Wave Analyzer at pre-LASIK and 1 month after the surgery. Then compared these data.2. Instrument and test: All the patients were evaluated by the Allegretto Wave Analyzer at pre-LASIK and 1 month after the LASIK,3-4 similar maps from one test were selected to analysis with Zernike polynomial coefficients.We selected C7, C8, C12 coefficients and each RMS value for higher-order to analysis. 3. Statistics:Paired t-test were used to study the difference of higher-order abberation between pre-operation and post-operation in every group. Two independent sample t-test or t'-test were used to study the difference of higher-order abberation each two groups between pre-operation and post-operation.Results:1. At 1 month,each RMS value for higher-order showed a statistically significant increase after the two kinds of LASIK compared with the corresponding preoperative values (P<0.05).and C7, C8, C12 coefficients,RMS4 value increased especially.In the experimental group: C7, C8, C12 coefficients,RMS3-4 and RMSh value is respectively 1.14 times, 3.36 times, 1.47 times, 1.40 times, 1.42 times, 2.04 times, 1.84 times, 1.44times by the corresponding preoperative values in the low diopter group. In the midrange diopter group is respectively 1.92 times, 2.54 times, 4.33 times, 1.64 times, 2.42 times, 1.92 times, 1.61 times, 1.77times. and in the high diopter group is respectively 6.47 times, 7.32 times, 8.87 times, 2.08 times, 3.28times, 2.34 times, 3.17 times, 2.40times.2. Normal control group: C7, C8, C12 coefficients,RMS3-4 and RMSh value is respectively 2.01 times, 1.70 times,6.21 times, 1.42 times,2.37 times, 1.36 times, 1.17 times, 1.53 times by the corresponding preoperative values in the low diopter group. In the midrange diopter group is respectively 5.24 times, 5.28 times, 6.86 times, 2.60times, 2.43 times, 1.58times, 2.06times, 2.29times. and in the high diopter group is respectively 6.37 times, 7.46 times, 5.58 times, 2.29 times, 3.37 times, 1.79times, 2.66times, 2.45 times3. The comparation between pre-operation and post-operation of aberration proportion in two groups :The lower-aberration of all the patients were statistically significant reduced after operation,but coma were statistically significant increased.4. In the low and midrange diopter groups,the accretion values of C8 between postoperation and preoperation in the normal control group were statistically significant increased than the experimental group. But in the high diopter groups,this situation was not exist. 5. The other accretion values were not significant different between the experimentalgroup and normal control group. Conclusions:1. Either LASIK with aggle Kappa adjusted or custom LASIK can cut down lower order aberration significantly,and correct myopia and astigmatism,on the other hand, increase higher order aberration significantly.2. LASIK with aggle Kappa adjusted can cut down the accretion of level coma compare with custom LASIK for low diopter myopia.3. LASIK with aggle Kappa adjusted can cut down the accretion of level coma compare with custom LASIK for midrange diopter myopia.4. LASIK with aggle Kappa adjusted is not significant different to custom LASIK for high diopter myopia on coma increasing.5. There were no significant differences on increasing of C12 and the other higher order aberration between LASIK with aggle Kappa adjusted group and custom LASIK group.