Comparison of retaining or removing negative vertical coma in wavefront guided LASIK for myopia and astigmatism

Objective To investigate the efficacy and safety of wavefront guided(WG)LASIK for the mvopia and astigrnatism.Methods This study is a randomized control trial.42 cases(78 eyes) were collected in the studv through the routine examinations and wavefront analysis,which were divided into two groups(A and B).The value of Z(3,-1)being less than-0.15μm was evaluated as Group A(24 cases,45 eyes):The value of Z(3,-1)being more than+0.15 μm was as Group B(18cases,33eyes).Both A and B were also divided into two subgroups(test and control).WG-LASIK was performed in tested groups,and classic LASIK was performed in control group. Visual quality,wavefront examination,and CSF were analyzed after surgery 3-6 months compared with that of preoperation. Results In the earlier period of postoperation time,diopters of the two groups were both slightly overcorrected, and then began to decrease slightly later and the diopters of both tested and control groups were corrected perfectly.RMSh of tested group increased higher than that of control group when Z(3,-1)was negative and the CSF in control group was better than that in test group after WG-LASIK in Group A.RMSh of tested group increased lower than that of control group when Z(3,-1)was positive and the CSF in tested group was better than that in control group after WG-LASIK in Group B.Conclusions These results suggest that retaining negative vertical coma and removing positive vertical coma were beneficial to the visual function after the WG-LASIK,which could save the corneal tissue reasonably in order to improve visual quMity effectively.(Chin J Ophthalmol,2008,44:217-222) Key words: Keratomileusis,laser in situ; Myopia; Asfigmatism;