Eyeworld

EW REFRACTIVE SURGERY 66 March 2016 by Michelle Dalton EyeWorld Contributing Writer communications. It would be nice to see a clinical trial," she said. The inlays may have a better biocompatibility profile if/when they're placed deeper (pockets tend to be deeper than 200 microns, flaps somewhere around 150–170 mi- crons). ReVision Optics uses a flap at this time but is working on a pocket technology for placing the inlays, Dr. Hovanesian said. While the KAMRA uses a pin- hole effect, the Raindrop changes the anterior corneal curvature, so the placement of the inlay "has to be more shallow—around 150–180 microns," Dr. McDonald said. "The Flexivue and KAMRA are much deeper, with the Flexivue at 280–300 microns and the KAMRA at least 200 microns. They're not working by changing anterior corneal curvature, and the keratocytes are happier when those implants are implanted deeper." Inlays that are too anterior will start to melt, Dr. McDonald said. The Raindrop needs a deeper incision, "but not so deep that it won't change the anterior corneal curvature," she said, adding pockets have a "huge advantage" over flaps because they induce less dry eye, and if the entry point is placed close to the limbus, they should induce less astigmatism. "But pockets have to be big enough that you can center the inlay properly over the Purkinje reflex," she warned. Deeper is better from a biocom- patibility standpoint, but can't be too deep, "so unless you're superfi- cial enough that the thickness of the inlay affects the curvature, you won't get any effect," Dr. Hovanesian said. The KAMRA relies more on the opacity of the inlay itself to create the optical ef- fect, "so depth isn't as much of an issue," he added. Some surgeons are evaluating "PLK2," or post-LASIK KAMRA, where LASIK is the first procedure, but the pocket is created simulta- neously, Dr. Cummings said. "The pocket is created at about 200 mi- crons below the surface, taking into account the ablation depth that the LASIK will consume, then the LASIK is performed and the flap replaced. After 4 weeks when the eye has settled, the pocket is accessed and Optics, Lake Forest, Calif., and Flexivue, Presbia, Dublin), implan- tation techniques are still being tweaked and perfected, but fall into one of two categories—a corneal pocket or a LASIK-like flap set at much deeper levels than a tradition- al flap. Each technique boasts advan- tages, but each has its detractors as well. Pocket implantation creates less trauma and severs fewer corneal nerves, meaning there is likely less drying and less risk of ectasia, said John Hovanesian, MD, clinical instructor, Jules Stein Eye Institute, Los Angeles. However, if the inlay needs to be removed or if there is an epithelial ingrowth, "managing that is a new type of challenge, and we don't have a lot of experience. There's very little published data," Dr. Hovanesian said. In the past, some European surgeons were combining LASIK and KAMRA—dubbed simLASIK— with a flap depth of about 200–230 microns, said Arthur Cummings, MD, FRCS, consultant ophthalmol- ogist, Wellington Eye Clinic, Dublin. They'd perform the ablation first, implant the inlay, then close the flap; LASIK could correct the refrac- tive error while the inlay addressed the presbyopia. Depth of incision Over time, "one of the most critical things that we've discovered is the importance of the spot line separa- tion," said Marguerite McDonald, MD, in private practice, Ophthal- mic Consultants of Long Island, Lynbrook, N.Y.; clinical professor of ophthalmology, New York Universi- ty Langone Medical Center; and ad- junct clinical professor of ophthal- mology, Tulane University Health Sciences Center, New Orleans. Fewer spots spaced farther apart results in a shorter ablation time, but also a rough surface. "AcuFocus has stud- ied this exhaustively," she said, "and visual results are better with 6 x 6 or less; healing is quicker." Because LASIK flaps are much closer to the surface than inlay flaps, most surgeons will separate the two procedures by about a month, Dr. McDonald said. "It hasn't been extensively stud- ied, but that's what most surgeons seem to be doing based on personal W ith one corneal inlay approved for use in the U.S. (KAMRA, AcuFocus, Irvine, Calif.) and others in development (Raindrop, ReVision When it comes to corneal inlays, pockets may become the preferred placement technique Pocket or flap? Device focus Advancing CATARACT SURGERY LenSx ® LASER ® © 2015 Novartis 7/15 CNT15039JAD-A CENTURION ® VISION SYSTEM IMPORTANT PRODUCT INFORMATION CAUTION: Federal (USA) law restricts this device to sale by, or on the order of, a physician. As part of a properly maintained surgical environment, it is recommended that a backup IOL Injector be made available in the event the AutoSert ® IOL Injector Handpiece does not perform as expected. INDICATION: The Centurion ® Vision System is indicated for emulsification, separation, irrigation, and aspiration of cataracts, residual cortical material and lens epithelial cells, vitreous aspiration and cutting associated with anterior vitrectomy, bipolar coagulation, and intraocular lens injection. The AutoSert ® IOL Injector Handpiece is intended to deliver qualified AcrySof ® intraocular lenses into the eye following cataract removal. The AutoSert ® IOL Injector Handpiece achieves the functionality of injection of intraocular lenses. The AutoSert ® IOL Injector Handpiece is indicated for use with the AcrySof ® lenses SN6OWF, SN6AD1, SN6AT3 through SN6AT9, as well as approved AcrySof ® lenses that are specifically indicated for use with this inserter, as indicated in the approved labeling of those lenses. WARNINGS: Appropriate use of Centurion ® Vision System parameters and accessories is important for successful procedures. Use of low vacuum limits, low flow rates, low bottle heights, high power settings, extended power usage, power usage during occlusion conditions (beeping tones), failure to sufficiently aspirate viscoelastic prior to using power, excessively tight incisions, and combinations of the above actions may result in significant temperature increases at incision site and inside the eye, and lead to severe thermal eye tissue damage. Good clinical practice dictates the testing for adequate irrigation and aspiration flow prior to entering the eye. Ensure that tubings are not occluded or pinched during any phase of operation. The consumables used in conjunction with ALCON ® instrument products constitute a complete surgical system. Use of consumables and handpieces other than those manufactured by Alcon may affect system performance and create potential hazards. AES/COMPLICATIONS: Inadvertent actuation of Prime or Tune while a handpiece is in the eye can create a hazardous condition that may result in patient injury. During any ultrasonic procedure, metal particles may result from inadvertent touching of the ultrasonic tip with a second instrument. Another potential source of metal particles resulting from any ultrasonic handpiece may be the result of ultrasonic energy causing micro abrasion of the ultrasonic tip. ATTENTION: Refer to the Directions for Use and Operator's Manual for a complete listing of indications, warnings, cautions and notes. continued on page 68

• Cover