Eyeworld

NOVEMBER 2019 | SUPPLEMENT TO EYEWORLD | 5 Power calculations and astigmatic outcomes unexpectedly fail in the oper- ating room," she said. Conclusion Careful preoperative marking and alignment are critical to achieving success in manag- ing astigmatism with toric IOLs. Residual astigmatism can affect patients' vision and postoperative satisfaction. n References 1. Koch DD, et al. Contribution of posterior corneal astigmatism to total corneal astigmatism. J Cataract Refract Surg. 2012;38:2080–2087. 2. Bauer NJ, et al. Astigmatism man- agement in cataract surgery with the AcrySof toric intraocular lens. J Cataract Refract Surg. 2008;34:1483– 1488. 3. Elhofi AH, et al. Comparison between digital and manual marking for toric intraocular lenses: a randomized trial. Medicine (Baltimore). 2015;94:e1618. Dr. Fram is the managing partner of Advanced Vision Care and is a clinical instructor at the Stein Eye Institute, University of California, Los Angeles. She can be contacted at DrFram@avceye.com or 310- 229-1220. continued from page 4 Zaina Al-Mohtaseb, MD Optimizing outcomes with available toric IOLs O btaining excellent visual outcomes from today's toric IOLs requires meticulous attention preoperatively, intraoperative- ly, and postoperatively. Daniel Chang, MD Daniel Chang, MD, and Zaina Al-Mohtaseb, MD, offer pearls for such optimization. Focus on precise measurements Dr. Chang stressed the impor- tance of a good quality biom- eter and an optimized ocular surface before measurements. This helps determine if the patient is a candidate for a toric IOL and to identify the degree of astigmatism. He takes the following steps: 1. Biometry measurements are ideally performed before refraction, tonometry, pupil dilation, or other assess- ments, which may disrupt the ocular surface. 2. Measurements are repeated for consistency, on separate days if possible, or at least after dilation. If they are consistent, he is more confi- dent in their accuracy. 3. Inconsistent results are a sign of ocular surface prob- lems. After treating the ocu- lar surface, if biometry does not stabilize, he reconsiders a premium IOL approach. Dr. Chang explained that corneal topography and other tests help the clinician determine the quality of the measurements. "The ocular surface can be a significant source of error," he said. "While a topographer does not produce the biome- try-quality keratometry needed for calculations, it does provide a big-picture overview of the state of the ocular surface." Most biometry devices have a number of built-in formulas. He recommended the Barrett II formula, which he said is robust throughout the range of axial lengths. In addition, he said, IOL man- ufacturers offer toric calcula- tors, some of which account for the posterior cornea and include a nomogram from the IOL clinical trials. Attaining optimal outcomes It is important to have a reli- able way to translate preop- erative data intraoperatively, Dr. Chang said. Alignment techniques range from manual marking methods to digital tracking and marking systems. Dr. Chang takes a "mid- dle-of-the-road approach," us- ing the topographer's eye im- age, along with the biometry data, to calculate the axis of correction. "After determining my desired axis, I transpose that information onto the eye by using the pupil and limbus structures to make sure I line with the intended axis," he said. He stressed the impor- tance of a quality, self-sealing wound. "I am meticulous with wound construction, because postoperative hypotony can lead to unpredictable lens movement," he said. After IOL implantation, he completely removes the viscoelastic and rotates it at least 180 degrees to make sure it sits well in the bag and the retrolenticular viscoelastic is gone. continued on page 6

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