EyeWorld India June 2015 Issue

10 June 2015 EWAP FEATURE the refractive index rather than the shape of the cornea, he added, but does result in about a line of distance vision lost. One advantage to the KAMRA is it offers good intermediate vision and a continuous range of vision, but because it creates a pinhole effect, night vision is slightly reduced, Dr. Lindstrom said. Similarly, the Raindrop boasts all the advantages of multifocal lenses, “but it has the potential for all the negatives, too, including loss of quality, loss of contrast, and halos at night.” The Raindrop is steeper in the center than in its intermediate areas, Dr. Whitman said, but patients may lose up to a line of distance vision. “They tend to regain a lot of it back over a year’s time,” he said. While some complain about the KAMRA’s visibility, Dr. Whitman said the 2-mm diameter, 30-µm thick Raindrop is imperceptible in a patient’s eye. Simply put, the inlays are trying to create a surgical alternative to monovision and multifocal contact lenses, Dr. Lindstrom said. There is also the VisAbility Implant and VisAbility Implant System (VIS) from the Refocus Group (Dallas). It is made of four small, clear plastic implants that are inserted below the surface of the sclera. The implants work through the vaulting of the sclera, according to the company’s website. “This vaulting of the sclera also lifts the underlying ciliary muscles surrounding the crystalline lens,” material from the company said. “Lifting of the ciliary muscles increases the [circumlental space], thus tightening the zonules that hold the lens in place. With proper tension on the zonules, the ciliary muscles can once again manipulate and change the shape of the lens to focus on near objects.” Pros and cons For John Doane, MD , FACS, in private practice at Discover Vision Centers, Kansas City, Mo., however, there are no attributes of the inlays that make him prefer them over monovision. “A pinhole will create increased depth of focus. Certain levels of asphericity and spherical aberration can also increase the range of usable vision. With the latter two there can and will always be a trade-off in the quality of the image,” he said. “Quality of vision and contrast sensitivity will be negatively affected. Conversely, one can maintain quality of vision by utilizing monovision or setting one eye for near focus, i.e., a –2 D residual refractive error.” With monovision, the trade- off is that for some patients, fusion is disrupted and some brains will not tolerate this, he said. “Probably close to 30% of patients cannot accept monovision,” he said. “For the 70% that do, best distance vision will be reduced [to] a certain degree.” Finally, there may be scotopic, unwanted imagery so bothersome that spectacles may be necessary— thereby depleting the advantages of surgery in the first place, he said. Dr. Thompson said he rarely has a patient who wants to have the inlay removed, certainly fewer than those with monovision who want the effect reversed. “The main reason is because inlays give not only good near and intermediate effect, but they preserve distance better. You’re not dealing with such distance blur, so there’s high patient satisfaction,” he said. The “whole basis of corneal inlays is to be able to have 20/20 distance vision, but still have a reading eye,” Dr. Thompson said. “Like a multifocal implant after surgery, that gives you 20/20 distance and good near.” Monovision in a 55-year-old often means targeting –1.5 D to –2 D, Dr. Thompson said. Inlays do not require blurring distance nearly as much as this level of monovision does. Inlays provide good binocular distance vision, as they do not interfere with distance, and “very good reading vision,” Dr. Whitman said. For him, the biggest drawback is that any of the known potential complications with making LASIK flaps exist for the inlays, as the KAMRA is placed in a pocket under a flap, and the Raindrop is placed directly under the LASIK flap. The Flexivue comes in different powers, which Dr. Whitman thinks may be a disadvantage. “As people age, our power needs change,” he said. “So what happens 5 years after the Flexivue is implanted? A lens exchange? I don’t think that’s the best platform. The KAMRA and the Raindrop do not depend on a power to work.” Dr. Doane said the ease of removal, exchange, and repositioning are all welcome features in an inlay, but unacceptable vision or actual biologic incompatibility “may not be noticed in the first 6 months. It is important to assess biological compatibility 12–24 months after implantation,” he said. Some patients are simply going to develop an inflammatory reaction, Dr. Whitman said. “We can try to treat that with steroids, but for some patients, inflammation will persist.” Dr. Doane said: “These products run a 24/7/365 risk of acute intervention. Corneal surgeons need to become corneal internists—always ready with medicines to calm down the eye.” Not every patient will have such a dire reaction, “but it is a certain percentage, and every doctor will, in time, find his or her number.” Surgeons need to remember that “the inlay is still an implant,” Dr. Thompson said. “Watch the patient for any dry eye symptoms because inlays do their best when tear film is healthy,” he said. Even with all the potential negatives, Dr. Whitman said “there’s no comparison in terms of binocular vision improvement. It’s a dramatic leap forward versus monovision.” Anterior segment specialists have had “the exact same argument at every meeting. What’s better: multifocal vision or monovision or modified monovision? It turns out that all three can work well. There isn’t a right answer. You just need to understand the differences,” Dr. Lindstrom said. EWAP Editors’ note: Drs. Lindstrom and Thompson have financial interests with AcuFocus. Dr. Doane has no financial interests related to his comments. Dr. Whitman has financial interests with ReVision Optics. Contact information Doane: jdoane@discovervision.com Lindstrom: rllindstrom@mneye.com Thompson: vance.thompson@vancethompsonvision.com Whitman: whitman@keywhitman.com Correcting - from page 8