Assessment of toric intraocular lens alignment by a refractive power/corneal analyzer system and slitlamp observation Paul J. Carey, MSc, Antonio Leccisotti, MD, PhD, Victoria E. McGilligan, PhD, Ed A. Goodall, PhD, C.B. Tara Moore, PhD PURPOSE: To assess the validity of an internal optical path difference map of a refractive power/ corneal analyzer system in determining the alignment of toric intraocular lenses (IOLs). SETTINGS: Private practices, Spring Hill, Brisbane, and Chermside, Australia. METHODS: This retrospective study comprised patients with more than 1.5 diopters of preexisting corneal astigmatism who had phacoemulsification and AcrySof toric IOL implantation. Preopera- tively, the surgical eye was marked at the slitlamp microscope using a 4-point technique. The desired IOL orientation was marked with a Mendez marker based on the steep corneal axis. The t IOL axis was measured 3 weeks postoperatively by rotating the slitlamp beam to align with the IO axis indicator marks and using the Internal OPD Map on the Nidek OPD-Scan system. Uncorrected (UDVA) and corrected (CDVA) distance visual acuities, residual refractive sphere, and residual keratometric and refractive cylinders were also measured at 3 weeks. RESULTS: Postoperatively, the mean UDVA was 0.17 logMAR G 0.18 (SD) and the mean CDVA, 0.01 G 0.12 logMAR; 88.2% of eyes had a UDVA of 0.3 or better, and no eye lost lines of visual acuity. There was an 82.33% reduction in defocus equivalent and a 64.62% reduction in refractiv cylinder. The mean IOL misalignment measured by slitlamp was 2.55 G 2.76 degrees and by the internal map, 2.65 G 1.98 degrees. The correlation between the 2 methods was highly significant (r Z 0.99, P<.001). CONCLUSIONS: Both refractive power/corneal analyzer system and slitlamp observation were reliable and predictable methods of assessing IOL alignment. The 4-point preoperative marking technique yielded clinically acceptable, accurate toric IOL alignment. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned. J Cataract Refract Surg 2010; 36:222–229 Q 2010 ASCRS and ESCRS A recent advance in cataract surgery was the introduc- tion of toric intraocular lenses (IOLs) for the correction of astigmatism. 1 Astigmatism,a common refractive error found in 15% to 29% of prospective cataract patients, 2–4 is caused by the corneal shape, crystalline lens shape, or a combination. Implantation of a toric IOL at the time of cataract removal is a predictable, sin- gle-step procedure to minimize residual refractive error. 5 The toric IOL has different optical powers in differ- entmeridians;therefore,the IOL must be correctly aligned to neutralize the astigmatism in the cornea. Each degree oferror in alignmentof the toric IOL reduces the cylinder power effect by approximately 3.3%. 6,7 A toric IOL placed 30 degrees off axis would provide no correction for astigmatism and would actu- ally induce further refractive error. It is well estab- lished thatpositionally induced cyclotorsion isan important factor when correcting astigmatism in cata- ract and refractive surgery. 8–12 A variety of techniques, devices,and methods are used to guide the surgeon when aligning the toric IOL. Numerous studies of the performance of excimer laser astigmatic surgery, toric IOLs, or phakic IOLs 13–19 describe different methods for marking the eye preoperatively. Most surgeons mark reference points on the cornea or limbus before surgery to actas a guide when implanting the IOL and to counteract cyclotorsion that can occur when Q 2010 ASCRS and ESCRS 0886-3350/10/$dsee front matter Published by Elsevier Inc. doi:10.1016/j.jcrs.2009.08.033 222 ARTICLE