Eyeworld

NOV 2012

EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.

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32 32 EW REFRACTIVE SURGERY November 2012 Phakic IOLs still on periphery by Michelle Dalton EyeWorld Contributing Writer Although visual outcomes slightly favor phakic IOLs over LASIK in moderate myopes, the lenses are still not as popular an option P hakic IOLs have numerous advantages over laser vision correction, not the least being "sharper, clearer vision," said Neil J. Friedman, M.D., adjunct clinical associate professor, Stanford Univer- sity School of Medicine, and director of cataract and lens implant surgery, Pacific Vision Institute, San Fran- cisco. Two phakic IOLs, the Visian ICL (STAAR Surgical, Monrovia, Calif.) and the Verisyse (Abbott Medical Optics, Santa Ana, Calif.), are approved in the U.S., and a third, the Cachet (Alcon, Fort Worth, Texas), is in clinical trials. Phakic IOLs are removable, which is advantageous for cataract IOL calculations, added Gregory D. Parkhurst, M.D., in private practice, Slade & Baker Vision, Houston. And reasons to exclude a potential candi- date for LASIK (i.e., poor surface or severe surface disease, abnormal or suspicious topography, or thin corneas) do not apply for a phakic lens, said Paul Harton Jr., M.D., in private practice, Harbin Clinic Eye Center, Rome, Ga. For mild myopes (in the –3 to –4 D range), "LASIK has reached such a critical mass most people know they're potential candidates," Dr. Harton said. Although he pres- ents both surgical options for the correction of these mild refractive errors, "most people usually decide on LASIK at that level, simply be- cause they know it better," he said. For patients with more moderate levels of myopia—at or above –5 D— the decision becomes a bit more in- volved. "Then it's a quality of vision difference, and it's better with a phakic IOL in moderate and severe myopes," Dr. Harton said. A good number of Dr. Friedman's patients are either not candidates for LASIK (thin corneas or out of range), but if all things were considered equal, he's more comfortable about potential visual outcomes with phakic lenses begin- ning at above –5 D. "Some LASIK ablations may limit what kind of IOL the patient can receive in cataract surgery," Dr. Parkhurst said. "And once patients hit presbyopia in their 40s or 50s, surgical treatments may be more limited if they've had previous LASIK." Other considerations When Dr. Parkhurst was in the mili- tary, his group retrospectively evalu- ated outcomes in more than 200 patients who had been implanted with the ICL. "One of our key find- ings was that we achieved 96% 20/20 at 3 months," he said. "In that group, the subjective and objective results were excellent. Phakic IOLs provided more of a 'wow' factor." A second prospective study compared wavefront-optimized LASIK and ICL implantation. Patients were matched for refractive errors, but Dr. Parkhurst added that in the military, "the ICL is used as a back-up option for personnel who are otherwise disqualified from LASIK." In this study, the average spherical equivalent was "about –6.2 D," he said. Patients in the LASIK group had slightly more astigma- tism; patients in the ICL group had slightly thinner corneas and some had cones. "What we found was a signifi- cant improvement in night vision and contrast sensitivity in the ICL group, which we did not see after LASIK," he said. "We did find it in- teresting that there was a non-signif- icant trend toward improvement in night vision in the LASIK cohort as well. We also looked at higher order aberrations (HOAs) and found LASIK induced more (there were no HOAs induced after the ICL)." Dr. Friedman said the findings didn't surprise him, as there are "several" advantages to a phakic lens over LASIK, including the immedi- acy of improved vision, minimal discomfort, no induced HOAs, and virtually no dry eye during the post- op recovery period. That's not to say phakic IOLs are without potential disadvantages, however. For one, "although we're avoid- ing corneal complications associated with laser vision correction, there are potentially more sight-threaten- ing complications than there would be with any intraocular lens sur- gery," Dr. Friedman said, although none of his patients have developed post-op complications. There is the potential for endothelial cell loss, earlier cataract formation, and a slight risk of glaucoma. Dr. Parkhurst added the risk to develop endophthalmitis is "essen- tially zero" after LASIK, and about 1:6,000 for the ICL. Additionally, phakic lenses present potential endothelial cell issues in the long term that are not present for a post-op LASIK patient. "Sizing is absolutely crucial on A phakic IOL unfolding Source: Paul Harton Jr., M.D. posterior chamber phakic IOLs. If the Visian ICL selected is too short, you increase your risk of cataract formation," Dr. Harton said. He uses high-resolution ultrasound biomi- croscopy (UBM) to ensure he has the right size lenses, and advises surgeons to use the sulcus-to-sulcus measurements in lieu of white-to- white to ensure correct vaulting without crowding the anterior chamber. Peripheral iridotomy Implantation of the Visian ICL requires a peripheral iridotomy (PI), but if surgeons create a PI that's too large, "it can cause visual issues," Dr. Harton said. "There are potential aesthetic issues as well if you have a big PI and a young, blue-eyed patient." If the PI is not open or occludes, angle closure or aqueous misdirection are also potential con- sequences, he added. All three surgeons agreed—"the best method for a PI is not to need one," Dr. Harton said. The Visian V4c lens does not require a PI, but is not yet available in the U.S. (it's being used in Europe). Per FDA la- beling, the Visian requires two PIs superior at "10 and 2 o'clock," but Dr. Harton has a new technique that creates a single pre-op PI without pilocarpine followed by an intraop- erative enlargement. In his two-step technique, a small PI is created in the office (which often can be confirmed as open with an aiming beam); the PI is then enlarged dur- ing surgery. "In the office, you're just pruning the stroma down to pigment epithelium," he said. Other advantages to the tech- nique include no pilocarpine use, better size control, and no addi- tional equipment needed. Phakic IOLs should not just be considered as an alternative to laser procedures, but should be at the forefront of conversations with patients, Dr. Friedman said. Dr. Parkhurst educates patients and offers the ICL throughout the FDA approval range, preferring patients with limited astigmatism (nearly spherical), above the –3 D range, and those with adequate anterior chamber depth. "Phakic IOLs are a good pre- mium option for refractive patients who want out of their glasses," he said. EW Editors' note: Drs. Friedman and Harton have no financial interests related to this article. Dr. Parkhurst has financial interests with STAAR Surgical. Contact information Friedman: 415-922-9500, neil@pacificvision.org Harton: 706-233-8502, pharton@harbinclinic.com Parkhurst: 713-626-5544, GDP@visiontexas.com

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