EyeWorld Asia-Pacific December 2014 Issue

41 EWAP REFRACTIVE December 2014 option of being able to do an intrastromal procedure in one step without a flap is exciting. “In general we have the same visual and refractive results as LASIK, but our experience and the literature support less dry eye and improved corneal sensation with the SMILE procedure,” he said. The possibility of improved biomechanics is another advantage. “The incision through the epithelium, Bowman’s, and the underlying stroma is much smaller compared to the size of the side-cut incision made during LASIK, and thus subsequent foreign body sensation is minimal and transient with the SMILE procedure,” he said. The photodisruption with SMILE is also advantageous, Dr. Doane said. “The glaring difference between femtosecond laser photodisruption and excimer laser refractive procedures is that with excimer laser techniques, the cornea stroma being treated is exposed to the environment of open air, so relative humidity, the speed with which the procedure is completed, temperature, barometric pressure, and air purity that the excimer laser beam are exposed to can vary from case to case, surgeon to surgeon, and locale to locale,” he said. With the SMILE technique because the photodisruption is done in a relative vacuum intrastromally within the cornea and the epithelium is not disrupted, the environmental factors will not impact outcomes. “This is a significant factor in moderate and higher myopic treatments,” Dr. Doane said. Disadvantages of SMILE As this is a new procedure, there are still some issues that need to be worked out. Dr. Doane said that the exact range of the technique is not currently known, and it is uncertain if compound myopic astigmatism, mixed astigmatism, and simple or compound hyperopic astigmatism can all be treated. Another issue is how to enhance patients undergoing this technique if that need arises. “At present we are left with creating a LASIK flap by extension of the small incision of SMILE and reflecting the flap and ablating with an excimer laser in a LASIK- like retreatment, or we have to do PRK,” he said. When compared with LASIK, the visual recovery after SMILE is slightly slower, Dr. Thompson said. Additionally, the lenticule extraction requires the surgeon to be comfortable with lamellar corneal dissection, so this means there would be a learning curve. “Like any surgery there are risks,” he said. “When dissecting in a lamellar fashion, if the surgeon is too aggressive or if there is an undiagnosed corneal scar, a cap perforation can occur in the SMILE procedure just like a flap perforation can occur in LASIK.” Does SMILE have the potential to replace LASIK? Dr. Doane thinks that SMILE has the potential to replace or compete commercially with LASIK “for simple and compound myopia of all ranges that is suitable for corneal refractive surgery.” The technique has great predictability for both higher and lower corrections. “As of February 2014, more than 100,000 SMILE procedures have been performed worldwide and more than 300 surgeons are certified,” Dr. Doane said. Despite hesitation and skepticism early on, he thinks that SMILE is now an accepted contender in refractive surgery in the U.S. Dr. Thompson thinks that the SMILE procedure has the potential to help numerous patients. “I predict that, like PRK and LASIK, we will find the best refractive errors and corneas to treat and that all 3 will coexist as options for patients who desire to lessen their dependency on optical devices,” he said. “The SMILE procedure is an exciting new procedure and like anything new, it deserves critical study and long- term follow-up. The early results have been very promising.” EWAP Editors’ note: Drs. Doane and Thompson have financial interests with Carl Zeiss Meditec. Contact information Doane: jdoane@discovervision.com Thompson: vance.thompson@vancethompsonvision.com still help. “The lenses I’ve been using for 20 years are clinically available, standard bifocal contact lenses for presbyopes,” Dr. Aller said. “The earlier you can start with something that’s at least moderately effective, the better the outcome will be 18 years down the road.” Based on the same principles, lined bifocal spectacles may also slow eye growth, Dr. Aller continued. In a group of Canadian children of Chinese descent with rapidly progressing myopia, use of bifocals slowed this by 40%. In his practice, Dr. Aller uses either bifocal contacts or Ortho-K as early as a child is willing to wear these. He stays away from atropine, unless there are no other options, noting that permanent changes in receptors in the eye have been found with its use. Going forward, a new treatment called 7-methylxanthine, a caffeine metabolite, is being considered. “Researchers found that children taking this in oral form had a dramatically lower rate of progression of myopia,” Dr. Aller said, adding that this does not have neural effects of caffeine. The treatment is currently being tried in Denmark and reviewed in the United States as well. EWAP Reference Aller TA. Clinical management of progres- sive myopia. Eye . 2014 Feb:28(2)147–53. Editors’ note: Dr. Aller has several patents in the area Contact information Aller: cptreyes@earthlink.net Slowing - from page 35