Eyeworld

EW FEATURE 34 by Michelle Dalton EyeWorld Contributing Writer In theory and in limited clinical data, the answer is: "Absolutely" W hen the femtosecond laser was introduced in refractive practices, few argued its superi- ority over manual mi- crokeratomes. In theory, femto for cataract is also likely to improve out- comes, "but by how much? The jury is still out on that one," said Steven C. Schallhorn, MD, in private practice in San Diego, and global medical director of Optical Express, Glasgow, U.K. In his opinion, "the primary area at this point" where the femto may be able to improve outcomes is in its ability to make a consistent and reproducible rhexis. "A precise and reproducible rhexis should improve the consis- tency of the lens position," he said. A more consistent lens position will lead to the ability to fine-tune lens power calculations and improve visual outcomes, he added. Sonia H. Yoo, MD, professor of ophthalmology, Bascom Palmer Eye Institute, Miami, explained the po- tential of the femto for cataract this way: "It's like sewing a hem on a pair of pants. If you have a really good seamstress, you'll probably get a good hem, possibly better than with a sewing machine. But with the machine, it's going to be consistent and it will be the same every time." According to William Trattler, MD, in practice at Center for Excellence in Eye Care, Miami, "The femto offers more reproducible results. We try to make every case as straightforward as possible and avoid deviation from what we're ex- pecting intraoperatively," he said. It's not just surgical technique where the femto will have an im- pact, predicted Mark Kontos, MD, in private practice at Empire Eye, Spokane, Wash. and Hayden, Idaho. The fastest-growing group of patients who opt for the laser are not necessarily those who want premium lenses, but those who want lower levels of astigmatism corrected. "Compared to what we used to be able to offer, the laser is going to have a greater positive impact on the refractive outcome of their sur- gery," he said. This patient group may have been relegated to AKs (Dr. Kontos disliked AKs as he "never got really tight results with them"), but now the femto can be used to create arcuate incisions with unequivocal precision. That, Dr. Kontos said, will allow surgeons to treat much lower levels of astigmatism with much more confidence. In theory Another area the femto should per- form better than manual processes is in creating corneal incisions, Dr. Schallhorn said. "The ability to place arcuate in- cisions in exactly the right location and depth and integrating iris imag- ing to ensure we stay on axis is a promising future enhancement with femto," Dr. Trattler added. The "one place" where surgeons will benefit from femto is in hitting refractive targets, Dr. Yoo said. "Ef- fective lens position (ELP) is hypoth- esized by different formulas. It's different for each patient, and leads to variability in refractive outcomes. That variable is non-existent in the corneal laser vision correction patient." Because a larger capsulorhexis allows the lens optic to come for- ward when the capsule contracts around the lens implant, the poten- tial exists for a slight myopic shift. Conversely, a smaller capsulorhexis may result in fibrosis, and a capsu- lorhexis that overlaps the optic on one side and is outside the optic on the other may result in lens tilt that would lead to astigmatism once the wound has healed, she said. In the- ory, those variables are eliminated with the femto. "Having a well-centered, perfect, reproducible rhexis is an important safety aspect of the surgery that should not be overlooked," Dr. Schallhorn said, especially for the less experienced surgeon. But "it will take many eyes to know whether or not there is a statistical difference," Dr. Yoo said. Refractive results of femtosecond laser cataract surgery June 2014 AT A GLANCE • Refractive results with the femto for cataract are approaching LASIK levels. • A precise and reproducible rhexis should improve the consistency of the lens position. • The fastest-growing segment may not be premium lens patients, but those who want lower levels of astigmatic correction. • Knowing how the capsule will behave in any patient may lead to novel IOL designs. Can the femto for cataract live up to its hype? Femtosecond lens segmentation Source: Sonia H. Yoo, MD 32-41 Feature_EW June 2014-DL_Layout 1 6/3/14 12:31 PM Page 34

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