Accuracy of toric intraocular lens implantation in cataract and refractive surgery

PURPOSE: To determine the accuracy of a commonly used 3-step procedure for toric pseudophakic and phakic intraocular lens (IOL) implantation. SETTING: University Eye Clinic, Maastricht University Medical Centre, Maastricht, The Netherlands. DESIGN: Cohort study. METHOD: In this analysis of toric IOL implantation, 6 preoperative images of the eye per patient and the surgery video were obtained using a digital imaging system. All 3 steps for toric IOL implantation were analyzed as follows: reference axis marking, alignment axis marking, and IOL alignment. In addition, vector analysis was used to calculate the errors in toric IOL alignment. RESULTS: Forty eyes (26 pseudophakic, 14 phakic) were analyzed. The mean errors in reference axis marking, alignment axis marking, and toric IOL alignment were 2.4 degrees +/- 0.8 (SD), 3.3 +/- 2.0 degrees, and 2.6 +/- 2.6 degrees, respectively. Together, these 3 errors led to a mean total error in toric IOL alignment of 4.9 +/- 2.1 degrees. Subgroup analysis showed no significant difference in mean error between pseudophakic IOL and phakic toric IOL alignment (P=.501). Vector analysis showed a mean angle or error of -2 +/- 8 degrees (pseudophakic IOLs) and 6 +/- 14 degrees (phakic IOLs). CONCLUSIONS: A commonly used 3-step ink-marker procedure to implant toric IOLs led to a mean error in IOL placement of approximately 5 degrees. The error was especially relevant in cases in which higher cylinder power IOLs were implanted. Orienting the toric IOL with great accuracy is necessary in all patients to achieve the best cylinder correction.