A Comparison Of Topography Supported Custom Ablation LASIK And Optimized LASIK In Myopic Eyes With Astigmatism

Objective:To compare the clinical outcomes of topography supported custom ablation LASIK (TOSCA-LASIK) and optimized LASIK (ASA-LASIK) in myopic eyes with astigmatism.Methods:Divide the enrolled myopic eyes with astigmatism(greater than-0.75D) into two groups randomly, performed respectively by topography supported custom ablation LASIK (TOSCA group) and optimized LASIK (ASA group) on the MEL80 excimer laser system (Carl Zeiss Meditec, Germany). Uncorrected vision acuity (UCVA), best-spectacle corrected visual acuity(BSCVA), manifest refraction, higher order aberrations (HOAs), contrast sensitivity and topography were measured and recorded preoperatively and at one month and three months postoperatively for each eye. The Alpins method was introduced to analyze the astigmatism correction. Statistical analysis was performed using SPSS 16.0 for Windows, a P value< 0.05 was considered significant.Results:LASIK was performed on 69 eyes of 38 patients and all of them were followed for 3 months. TOSCA was performed on 36 eyes while ASA was performed on 33. UCVA of 1.0 or better was achieved in 86.1%,94.4%of eyes in the TOSCA group and 78.8%,82.7%of eyes in the ASA group respectively at 1-and 3-month. Analysis of astigmatism correction with Alpins method:The AE by keratometry was significantly smaller in the TOSCA group compared to the ASA group in absolute means (p=0.014); The mean arithmetic ME demonstrate that the ASA group tends to undercorrect the astigmatism by 0.19 and 0.37D respectively by refraction and keratometry, while the TOSCA group overcorrect by 0.14 and 0.05D (P=0.000, P=0.012); The FI, CI and S.CI of the ASA group are all significantly smaller than those in the TOSCA group both by refraction and keratometry. The mean total high-order aberrations in the ASA group (0.600±0.146) was significantly higher than it in the TOSCA group (0.488±0.189) (P=0.007), at 3-month postoperatively, all mean HOA values between both groups were similar. Mean contrast sensitivity without glare was reduced slightly 3-month after the surgery in both groups at all target sizes and the significant differences appeared at 4.2 cpd (p=0.030) of the ASA group and 4.2,6.6,10.6 cpd (p=0.001, p=0.002, p=0.034) of the TOSCA group. The mean change in the without-and with-glare contrast sensitivity 3-month postoperatively showed no significant difference between both groups.Conclusions:Topography supported custom ablation LASIK (TOSCA-LASIK) in this study was safe, effective and predictable for the treatment of myopic eyes with astigmatism. Compared to the conventional optimized LASIK (ASA-LASIK), it reduced residual astigmatism and was more likely to have good visual acuity.