The Influence Of Two Calculate Methods On The Outcomes Of Toric Intraocular Lenses

Objective:The purpose of this study was to evaluation the influence of Barrett calculator and AcrySof calculator on astigmatism correction effect using vector analysis.Methods:This is a randomized prospective study.A total of 64 cases（81 eyes）who planed to undergo phacoemulsification at Tianjin Medical University Eye Hospital during January 2017 and March 2018 were enrolled and divided into two groups randomly,including of the Barrett calculator group of 34 cases（41 eyes）and the AcrySof calculator group of 30 cases（40 eyes）.Preoperative ocular biological parameters were measured using Lenstar LS900.The Toric intraocular lenses（IOL）plans were determined based on Barrett calculator and the AcrySof calculator for the two groups respectively.Subjective optometry was performed by phoropter and Toric IOL alignment was detected by slitlamp examination at 1 and 3 months postoperatively.Statistical analysis was taken with the data of 29 cases（35 eyes）in the Barrett calculator group and 26 cases（35 eyes）in the AcrySof calculator group,there were 20males（25 eyes）and 35 females（45 eyes）with an average age of（72±10）years.The difference between the predicted residual astigmatism by the two calculators and the residual astigmatism obtained by postoperative optometry is the error of refractive astigmatism（ERA）.The magnitude error（EM）is the algebraic difference of ERA.Error vector（EV）is a vector difference of ERA.Statistical analysis of magnitude error and VE between the two groups were taken by student’s t test.Results:At 1 months and 3 months,the magnitude error of Barrett calculator group were（0.19+0.16）D,（0.28+0.24）D,and that of AcrySof calculator group were（0.36+0.28）D,（0.46+0.41）D,and the differences were statistically significant（t=-3.050,-2.036,both P<0.05）.At 1 month postoperatively,the overall,with-the-rule astigmatism,and against-the-rule astigmatism EV of the Barrett calculator group were（0.30±0.21）D,（0.26±0.22）D,（0.37±0.26）D respectively,and that of the AcrySof calculator group were（0.47±0.33）D,（0.51±0.34）D and（0.52±0.38）D respectively,the difference between the two groups was statistically significant（t=-2.533,-2.436,-2.150,all P<0.05）.At 3 months postoperatively,the overall,with-the-rule astigmatism,and against-the-rule astigmatism EV of the Barrett calculator group were（0.37±0.28）D,（0.29±0.17）D,（0.35±0.27）D respectively,and that of the AcrySof calculator group were（0.59±0.46）D,（0.54±0.37）D,（0.64±0.52）D respectively,the difference between the two groups was statistically significant（t=-2.142,-2.038,-2.481,all P<0.05）.The difference of X_EV was statistically significant[-0.13（-0.36,0.80）D vs.0.19（-1.01,0.71）D,P<0.05],and the difference of Y_EV was statistically significant[-0.02（-0.51,0.64）D vs.-0.15（-0.88,1.10）D,P<0.05].There was no significant difference in X_EVV andY_EV（P>0.05）at 3 months.Conclusion:Compared with AcrySof Toric calculator,using Barrett calculator to select Toric IOL can reduce ERA and improve Toric IOL correction outcomes.