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T he key to achieving good visual results with toric IOLs is understanding the importance of stability of the IOL and the effect of rotation on vision. Even small amounts of rotation can result in significant cylinder power loss. For example, 1 degree of rotation causes a 3% cylinder power loss, 10 degrees causes a 35% loss, and 30 degrees causes a 100% loss. Additionally, 90 degrees of rotation doubles the amount of astigmatism. To determine the effect of residual astigmatism on vision, Steve Schallhorn, MD, conducted a study of 4,970 consecutive eyes undergoing multifocal IOL implantation. According to the study results, 81.3% of patients who had no postoperative cylinder had 20/20 uncorrected distance visual acuity (UCDVA), 54.3% of those with 1.0 D of postoperative cylinder had 20/20 UCDVA, and only 10.9% of those with 2.0 D of postoperative cylinder had 20/20 UCDVA. Residual astigmatism also has an effect on patient satisfaction. Be- cause patients are paying a premium for good refractive outcomes, they are obviously disappointed if their uncorrected visual acuity is not what they had hoped for. In Dr. Schallhorn's study, patients' satisfaction went down linearly as the amount of astigmatism went up. For example, 73.2% of patients with no postoperative cylinder said they were very satisfied, 66.9% of patients with 1.0 D of postoperative cylinder were very satisfied, and 47.1% of patients with more than 1.5 D of postoperative cylinder were very satisfied. Residual cylinder also exacer- bates glare and halos. In achieving good refractive outcomes and qual- ity of vision, surgeons aim to mini- mize both sphere and cylinder to have the best quality of vision. This is especially true with higher levels of cylinder correction. The effect of rotation is even more significant on quality of vision with a higher power toric lens than a lower power. In Dr. Schallhorn's study, 24.8% of patients with no postoperative cylinder had glare compared with 29.2% of patients with 1 D of postoperative cylinder and 28.6% of patients with more than 1.5 D of postoperative cylinder. Similarly, 24.9% of patients with no residual cylinder had halos, compared to 32.2% of those who had 1 D of residual cylinder and 35.7% of those who had more than 1.5 D of postoperative cylinder. Once surgeons understand the importance of stability in toric lenses, they will appreciate the Tecnis Toric (Abbott Medical Optics, Santa Ana, Calif.), which stays in the position it is implanted. Investiga- tors evaluated the rotational stability of the Tecnis Toric in a prospective, multicenter, two-armed study. The study was conducted at 14 sites in the U.S. and Canada. High-resolu- tion digital slit lamp retroillumina- tion photographs were analyzed using validated, axis-measurement software. The program used iris and/or scleral landmarks to align images from later time points with the baseline image of a given eye. More than 93% of all of the Tecnis Toric IOL first eyes had less than a 5-degree change in axis between their 1- and 3-month visits and between their 3- and 6-month visits, and the average was less than 3 degrees. The ANSI standard for a toric IOL is greater than 90% for a less than 5-degree axis change, so it well exceeded that standard. The 2013 ASCRS Clinical Survey found that surgeons' preferences are varied with regard to how to treat astigmatism. This survey was com- pleted in April 2013 and included 1,041 respondents. Of all the cataract surgeries performed in the United States, about 15% are toric. This percentage is higher (23%) outside the United States. Surgeons' opinions were mixed with regard to how to manage a patient with 1.25 D of astigmatism. Twenty-five percent of U.S. surgeons would manage this amount of astigmatism with LRIs or AK, approximately 50% of U.S. surgeons by Elizabeth A. Davis, MD, FACS Achieving good outcomes with toric IOLs "In Dr. Schallhorn's study, patients' satisfaction went down linearly as the amount of astigmatism went up." Elizabeth A. Davis, MD, FACS 8 Patient satisfaction goes linearly down as residual astigmatism goes up. Data courtesy of Optical Express Proper toric alignment is critical to ensure optimal outcomes. continued on page 15 Patient satisfaction D residual cylinder May 2014

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