Eyeworld

EW FEATURE 102 Advances in corneal inlays • March 2017 important. Placing an inlay too shallow in the cornea can result in haze and refractive changes, Dr. Rebenitsch said. For the KAMRA inlay, the in- dicated pocket depth is 200 to 250 microns. "However, more recent studies have shown that deeper pockets especially in thicker corneas can improve visual outcomes," he said. "In my practice, I typically aim for approximately 50% corneal depth allowing for 250 microns of stroma posterior to the inlay." Dr. Rebenitsch noted that for patients with previous refractive surgery, the inlay can still be placed, although it is considered off label. "In these patients, I want to maintain at least 80 microns of stroma between the pocket and the bed of the previous flap," he said. Meanwhile, for the Raindrop in- lay, the IDE study showed increased rates of haze and explant in patients who had a flap thickness less than 30%, Dr. Rebenitsch said, again stressing that pocket studies are cur- rently underway. "Although deeper implantation may improve the risk profile, there is concern that the vi- sual results may diminish due to less effective remodeling," he said. "In the early rendition of the KAMRA inlay surgery, the inlay was placed underneath a standard LASIK flap," Dr. Hoopes said. "Surgeons would use different thickness flaps." However, he noted that this has been abandoned because of issues of dry eye and cornea haze when the inlays were placed under a shallow flap. Now, the KAMRA as well as the Presbia Microlens (Presbia, Dub- lin, Ireland), currently under FDA investigation, are placed using a femtosecond pocket, he said. "It is now advised to place pockets at 250 microns deep or more with the KAMRA," Dr. Hoopes said. "The FDA study protocol for the Presbia Micro- lens was at 300 microns deep. The current protocol [for the Raindrop] is to make a femtosecond flap at 30% of cornea depth, which in our experience has been in the 175- to 180-micron depth range." Dr. Durrie also stressed that the choice between flap and pocket is directly linked to the type of inlay being used. For the KAMRA, it needs to be deeper than 200 microns. Dr. Durrie added that even if the patient already has a flap, you can't neces- sarily use that flap. It needs to be done deeper in the cornea, so the keratocytes are less dense with less wound healing. Femtosecond lasers are optimized for deeper, he added. Dr. Durrie said that using OCT ahead of time can help a surgeon know where the old flap is. There is good data starting to show that deeper is better. "With the inlays that are newer, we still need to work out what depth it should be," he said. EW Editor's note: Dr. Durrie has financial interests with AcuFocus, Abbott Med- ical Optics, and Alcon. Dr. Rebenitsch has financial interests with AcuFocus and Ziemer. Dr. Hoopes has financial interests with Carl Zeiss Meditec (Jena, Germany) and AcuFocus. Contact information Durrie: ddurrie@durrievision.com Hoopes: pchj@hoopesvision.com Rebenitsch: lrebenitsch@gmail.com SINGLE USE 16 % OFF volk.com /volk1 BUY IN BULK TODAY up to > Trusted Quality of Volk Optics > No More Reprocessing > Sterile Packaged in Boxes of 10 3-Mirror & 4-Mirror Gonio 1-Mirror SLT Capsulotomy & Iridotomy Surgical 20D & 28D BIO Surgical Vitrectomy One Use, Perfect Optics, No Hassle ULTIMATE PEACE OF MIND the creation of a thicker flap and placement of the inlay on the ablat- ed bed. "For the Raindrop, as we are not yet sure of pocket outcomes, this ablation could also be performed off label with placement of the inlay on the ablated bed," Dr. Rebenitsch said. The thickness of the anterior bridge of tissue in a pocket or the flap thickness are both incredibly Implanting continued from page 101

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