Eyeworld

FEB 2012

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

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76 EWInternational February 2012 International outlook Lenticule may beat LASIK in the dry eye arena by Matt Young EyeWorld Contributing Editor previously classified as unsuitable for LASIK, based on pre-existing dry eye conditions. "We are effectively preserving F emtosecond lasers continue to find new applications in ophthal- mology. In this article we learn from three experts that precision intrastromal refractive surgery may pre- serve corneal sensation and offer an im- proved safety profile for dry eye symptoms. The anatomical basis for this potential benefit certainly makes sense, but the clinical difference, if any, has yet to be carefully studied. What is clear is that corneal refractive surgery continues to be an active area for the application of new technology. It seems possible that fem- tosecond lasers may someday compete with LASIK, and we will continue to watch for further reports on this promising new treatment. John Vukich, M.D., international editor the natural neural arc systems that control the production of three components of the tear film: mucin, water, and oil," Dr. Reinstein said. He explained the nerves supply- ing the cornea run along its surface. With SMILE, the lenticule is re- moved from beneath where the nerves run, while the cap—and its nerves—remain intact. "We have measured corneal sen- sation on a Cochet-Bonnet aesthe- siometer," Dr. Reinstein said. "The normal range is 45-55. By 1 month, [SMILE patients] are back to 60— normal. For LASIK patients, it takes 6-12 months for corneal sensation to reach that level [again]. SMILE changes the landscape of the post- op recovery for the patient." Dr. Reinstein emphasized that while LASIK is a fast procedure—in- cluding the visual recovery aspect— dry eye sensations remain long after the procedure is over. "Using artificial tears for several SMILE procedure gears up to improve corneal sensation after refractive procedures D Watch video on your smartphone or iPad using your QR code reader. (Scanner available for free at your app store.) r. Shah's YouTube video is simple enough: It shows a straightforward SMILE (small incision lamellar extraction, Carl Zeiss Meditec, Jena, Germany) procedure to the tune of some Eastern music. For that, Rupal Shah, M.D., New Vision Laser Centers, Vadodara, India, received more than 7,000 hits and counting. SMILE, which has received regu- latory approvals outside of the U.S., is an entirely femtosecond refractive procedure, involving the excision of a lenticule from stroma with a femtosecond laser. It is extracted through a small incision, and no excimer laser is needed. "I think SMILE is very attractive, both for doctors and patients," said Dr. Shah. "Patients love the idea of not having a flap in the eye, which could possibly be one reason why they are looking for alternatives. A lot of eye surgeons watch the YouTube videos because they are evaluating whether to incorporate it into their practice." One point that surgeons and pa- tients should consider carefully is SMILE's impact on dry eye, or more importantly, the lack thereof. "The reason why corneal sensa- tion is reduced after LASIK is that the corneal nerves are cut, especially in the nasal-temporal regions," Dr. Shah said. "In SMILE, because of the small incision, and at the superior position, fewer nerves are cut, which certainly should make a difference to the corneal sensation and conse- quent dry eye." While the jury is still out on SMILE's evidence-based impact on dry eye—as more prospective studies are needed—advocates are con- vinced that the procedure will be a boon to those with this condition, and would-be sufferers too. Corneal sensation quickly recovered Dan Z. Reinstein, M.D., medical director, London Vision Clinic, London, believes SMILE will make refractive surgery available to people times a day for up to a year in LASIK patients happens," Dr. Reinstein said. "It's not a big price to pay from going blind to being able to see. But it's a heck of a nuisance." The procedure will help patients and also doctors, he said. "The greatest drag on post-op follow-up requirements that the surgeon needs to provide for pa- tients is with respect to dry eye," Dr. Reinstein said. "On the internet, LASIK-ruined-my-life types of web- sites are about dry eye sensation. Now, a procedure that can get around this major side effect is a massive advance for everyone." Phantom pain: Disappearing for good? Ilpo S. Tuisku, M.D., Ph.D., Helsinki University Eye Hospital, Finland, is optimistic about the pro- cedure as well. His Ph.D. thesis was on the topic of corneal nerves in refractive surgery and dry eye. Perhaps most importantly, he found that LASIK dry eye is a spectrum of disease states, which he divided into four categories: 1) neu- ropathic epitheliopathy, 2) tear fluid

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