OCT 2013

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

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86 EW REFRACTIVE SURGERY October 2013 Expanding options for phakic lenses by Rich Daly EyeWorld Contributing Writer A growing demand for phakic lenses may soon be met by a growing number of options A s U.S. regulators consider expanding the number and range of phakic intraocular lenses available to patients, surgeons caution that not all such lenses are created the same, with each carrying its own risks and rewards. Surgeons have accumulated a growing body of experience with two approved phakic IOLs, the Visian ICL (STAAR Surgical, Monrovia, Calif.) and the Verisyse irisfixated lens (Abbott Medical Optics, Santa Ana, Calif.). And at least two more lenses—the Cachet lens (Alcon, Fort Worth, Texas) and the Toric ICL (STAAR Surgical)—have been working their way through U.S. Food and Drug Administration trials. Since the first phakic IOL received U.S. regulatory approval in 2004, U.S. surgeons have discovered some of the same advantages these types of lenses have offered internationally. "We offer phakic IOLs to all patients seeking refractive surgery who have adequate anterior chamber depth and who fit within the dioptric range of lenses currently available in the United States," said Gregory D. Parkhurst, MD, in private practice, Slade & Baker Vision, Houston. Dr. Parkhurst, who teaches phakic implantation courses and wet labs at annual clinical meetings, has implanted the Visian ICL, the STAAR Toric ICL, and the Verisyse lens. Among the advantages he has found with phakic lenses are their removability, their lack of interruption of the neuroregulation of the corneal tear film, and their ability to offer superior vision quality by correcting refractive error near the optical nodal point of the eye. Additionally, phakic lenses "leave the eye with no permanent structural changes to the cornea, which may be of benefit for patients considering advanced technology refractive intraocular lens implants at the time of cataract surgery in the future," Dr. Parkhurst said. Specific phakic lenses come with their own advantages and disadvantages, according to surgeons experienced with them. Visian The Visian ICL, which is a collamer lens that was approved by the FDA in 2005 and well tolerated in the eye, is easily foldable for implantation through small incisions. The posterior chamber lens leaves no cosmetic issues and little risk of corneal damage through contact with the corneal endothelium. "The vision quality is superior to some other forms of refractive surgery as seen in head to head trials we and others have performed," Dr. Parkhurst said. Its disadvantages include the lack of a U.S. toric model, which necessitates additional steps to correct astigmatism. Another challenge is the required use of peripheral iridotomy, which is not required by the Visian ICL CentraFLOW, available internationally. Another Visian challenge noted by Majid Moshirfar, MD, professor of ophthalmology, John A. Moran Eye Center, University of Utah School of Medicine, Salt Lake City, is the importance of correctly selecting from among the lens' four sizes— depending on the patient's measurement. "If you choose a lens that does not match the sulcus-to-sulcus measurement then the surgeon may place a longer lens that can cause excessive vaulting of the lens; a shorter lens leaves too little vaulting and places the lens directly on the anterior capsule of the lens, which may lead to anterior subcapsular cataract formation," Dr. Moshirfar said. Verisyse The Verisyse lens, which was first approved for U.S. use in 2004, is a predictable refractive surgery technology that provides excellent visual acuity outcomes, Dr. Parkhurst said. However, its disadvantages include a rigid material that requires a larger incision and sutures, which may induce astigmatism. Additionally, cosmesis is problematic for some patients due to pupil ovalization. Finally, its design puts it at risk of dislocation and potential damage to the endothelium. The lack of an approved toric version of the Verisyse lens requires additional steps for correction of astigmatism. These factors make implantation of the Verisyse technically more challenging than the Cachet or Visian, Dr. Parkhurst said. Other Verisyse challenges noted by Dr. Moshirfar include the required use of retrobulbar anesthesia for many patients, and suture placements require a longer recovery time. Finally, centration of the irisanchored Verisyse lens is a little bit more challenging, which makes the overall learning curve steeper. STAAR Toric ICL The collamer STAAR Toric ICL also is well tolerated in the eye and easily foldable to fit through small incisions. The posterior chamber lens is not yet FDA approved, however the manufacturer was recently notified by the FDA that it plans to bring the product to its advisory panel, Dr. Parkhurst said. Disadvantages of the STAAR Toric ICL include the required use of peripheral iridotomy. Cachet The Cachet is comparably easy to place in the anterior chamber as it folds and fits through a small incision and does not require an iridotomy. The Cachet's disadvantages include the risk of endothelial cell loss due to its position in front of the iris. However, even though theoretically an anterior chamber placement is easier, it does offer its own challenges, and is not a widely popular phakic IOL in the countries where it has been approved for use, said Robert P. Rivera, MD, director of clinical research, Hoopes Vision, Draper, Utah. A particular concern is that unacceptable endothelial cell loss may be an unwanted compromise, given that this lens is much closer to the corneal endothelial cell layer. Pearls vary Surgeons can optimize their results from phakic lens by taking into account specific design elements of each type of IOL. For instance, preop planning is critical with the Visian lens, said Dr. Moshirfar. Specifically, it is impor- tant to have a very reliable whiteto-white and sulcus-to-sulcus measurement along the 180 degree meridian. He measures Visian patients with the Pentacam (Oculus, Arlington, Wash.) and the IOLMaster (Carl Zeiss Meditec, Jena, Germany) as well as manually with a caliper in the operating room in the supine position preoperatively. He believes sulcus-to-sulcus measurement with UBM technology is the gold standard that may not be available for all clinicians. Dr. Rivera said he has had a near zero cataract rate with the lens because he carefully selects the ICL size based on sulcus-to-sulcus UBM technology. The primary phakic IOL pearl emphasized by Dr. Rivera is for surgeons considering implantation of the lenses to first visit a practice that routinely uses them and learn the process from an experienced surgeon. "Besides the surgical procedure itself, it's equally important to get an idea of the preoperative workup, the patient discussion, and even the marketing approaches that are taken, given that this is still an elective refractive procedure that requires patients be willing to pay for their vision correction," Dr. Rivera said. Dr. Parkhurst said he anticipates continued growth in use of phakic IOLs when they are available in a wider range of powers and have fenestrations that negate the need for iridotomy, such as the Visian ICL models available internationally with "KS-Aquaport" technology. EW Editors' note: Dr. Moshirfar has no financial interests related to this article. Dr. Parkhurst has financial interests with STAAR Surgical. Dr. Rivera has financial interests with STAAR Surgical. Contact information Parkhurst: 713-626-5544, GDP@visiontexas.com Moshirfar: 801-694-5543, majid.moshirfar@hsc.utah.edu Rivera: 801-568-0200, rpriveramd@aol.com

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