Effects of posterior corneal astigmatism on the accuracy of AcrySof toric intraocular lens astigmatism correction

AIM:To evaluate the effects of posterior corneal surface measurements on the accuracy of total estimated corneal astigmatism.METHODS:Fifty-seven patients with toric intraocular lens(IOL) implantation and posterior corneal astigmatism exceeding 0.5 diopter were enrolled in this retrospective study.The keratometric astigmatism(KA) and total corneal astigmatism(TA) were measured using a Pentacam rotating Scheimpflug camera to assess the outcomes of AcrySof IOL implantation.Toric lOLs were evaluated in 26 eyes using KA measurements and in 31 eyes using TA measurements.Preoperative corneal astigmatism and postoperative refractive astigmatism were recorded for statistical analysis.The cylindrical power of toric lOLs was estimated in all eyes.RESULTS:In all cases,the difference of toric IOL astigmatism magnitude between KA and TA measurements for the estimation of preoperative corneal astigmatism was statistically significant.Of a total of 57 cases,the 50.88%decreased from T_n to T_(n-1) and 10.53%decreased from T_n to T_(n-2).In all cases,5.26%increased from T_n to T_(n+1).The mean postoperative astigmatism within the TA group was significantly lower than that in the KA group.CONCLUSION:The accuracy of total corneal astigmatism calculations and the efficacy of toric IOL correction can be enhanced by measuring both the anterior and posterior corneal surfaces using a Pentacam rotating Scheimpflug camera.