348 Copyright © SLACK Incorporated REVIEW REVIEW orneal astigmatism requiring surgical correction is fre- quently seen in patients undergoing cataract surgery. In two large studies involving 4,540 and 7,500 eyes, a corneal astigmatism 1 diopter (D) or greater was found, respectively, in 34 and 32.3% of cases. 1,2 The AcrySof Toric in- traocular lens (IOL) (Alcon Laboratories, Inc., Fort Worth, TX) was introduced in 2005 for the correction of preexisting corneal astigmatism. In 2011, the aspheric model replaced the initial non-aspheric one. The IOL design is based on the one-piece AcrySof platform. Toricity is added to the posterior surface. The overall haptic length is 13.0 mm and the optic diameter is 6.0 mm. Toricity at the IOL plane ranges from 1 to 6 D, which ac- cording to the manufacturer corresponds to a range of 0.67 to 4.50 D (Table 1). The purpose of this review is to analyze the clinical per- formance of this IOL in patients undergoing phacoemulsifica- tion/IOL surgery. PREOPERATIVE ASSESSMENT OF THE INTENDED ASTIGMATISM TREATMENT The aim of toric IOLs is to maximally correct corneal astigmatism. The intended change in cylinder, which can be more appropriately defined as the target-induced astigmatism (TIA), as suggested by Alpins, 3 is derived by adding (1) the preoperative corneal astigmatism and (2) the surgically in- duced change in corneal astigmatism (SICA). The resulting cylinder must be compensated for by the corneal plane cylin- der equivalent power of the IOL. ASSESSMENT OF PREOPERATIVE CORNEAL ASTIGMATISM Preoperatively, corneal astigmatism can be measured by means of one of the several technologies currently avail- C ABSTRACT PURPOSE: The AcrySof Toric intraocular lens (IOL) (Al- con Laboratories, Inc., Fort Worth, TX) is designed to correct corneal astigmatism ranging from 0.67 to 4.11 diopters (D). The authors reviewed the clinical outcomes of this IOL and investigated possible improvements of the online calculator provided by the manufacturer. METHODS: Review of published studies. RESULTS: The AcrySof Toric IOL can provide good re- sults, although a mean overcorrection or undercorrec- tion relative to the intended correction has been found by some authors. Stability over time has been reported to be excellent. Rotation occurs mainly in the first post- operative month and is greater in eyes with a longer axial length due to the larger capsule size. The online calculator of this IOL may be improved by considering the posterior corneal astigmatism and better calculating the conversion of the IOL cylinder from the IOL plane to the corneal plane, which may be inaccurate for two reasons. First, given the variable distance between the IOL and the cornea in short and long eyes, the fixed ratio (1.46) provided by the manufacturer cannot be used to calculate this conversion. Second, the online calcula- tor does not take into account the effect of varying IOL sphere power. CONCLUSION: The AcrySof Toric IOL is a reliable choice to correct corneal astigmatism at the time of cataract surgery. Results will be improved once the online cal- culator by the manufacturer considers the posterior corneal astigmatism and the variable ratio between the toricity at the IOL and corneal plane. [J Refract Surg. 2013;29(5):348-354.] From G.B. Bietti Eye Foundation-IRCCS, Rome, Italy (GS, PD); and Jules Stein Eye Institute, University of California, Los Angeles, and St. Mary’s Eye Center, Santa Monica, California (KJH). Submitted: December 19, 2013; Accepted: March 5, 2013 The authors have no financial or proprietary interest in the materials pre- sented herein. Correspondence: Giacomo Savini, MD, G.B. Bietti Eye Foundation-IRCCS, Via Livenza 3, 00198 Rome, Italy. E-mail: giacomo.savini@alice.it doi:10.3928/1081597X-20130415-06 A New Slant on Toric Intraocular Lens Power Calculation Giacomo Savini, MD; Kenneth J. Hoffer, MD, FACS; Pietro Ducoli, MD