Vector Analysis of Corneal and Refractive Astigmatism Changes Following Toric Pseudophakic and Toric Phakic IOL Implantation

Abstract

To determine the efficacy of the astigmatism correction following toric intraocular lens (IOL) and toric phakic IOL (pIOL) implantation in eyes with no previous ocular surgery and in postkeratoplasty (PKP) eyes. In addition, changes in corneal astigmatism were determined. Astigmatism was analyzed in 35 eyes with an AcrySof toric IOL, 35 eyes with an Artiflex toric pIOL, 50 eyes with an Artisan toric pIOL, and 40 PKP eyes with an Artisan toric pIOL. Refractive astigmatism was analyzed by using Alpins method. Surgically induced corneal astigmatism (SICA) was determined following a superior 2.2-mm, 3.4-mm, or 5.4-mm incision. Follow-up was 12 months. Following toric IOL implantation, the index of success was 0.14 and overall residual astigmatism, 0.37 diopter (D). Following toric pIOL implantation, the index of success was 0.32 (Artiflex) and 0.18 (Artisan), and overall residual astigmatism was approximately 0.60 D. In PKP eyes, Artisan pIOLs resulted in an index of success of 0.28 and overall residual astigmatism of 1.56 D. The SICA, following 2.2-mm, 3.4-mm, 5.4-mm (normal eyes), and 5.4-mm (PKP eyes) incisions, was -0.25 ± 0.42 D (P = 0.108), -0.31 ± 0.43 D (P < 0.001), -0.48 ± 0.55 D (P < 0.001), and -0.49 ± 1.48 D (P = 0.035), respectively. Toric IOLs and pIOLs provide an effective astigmatism correction. Incorporating the SICA into the toric IOL power calculation may further increase their effectiveness. Therefore, incorporation of 0 D, -0.30 D, or -0.50 D of SICA for a 2.2-, 3.4-, or 5.4-mm superior incision, respectively, is recommended.