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SUPPLEMENT TO EYEWORLD | DECEMBER 2021 | 5 Sponsored by Carl Zeiss Meditec enhancement rate of 2.7% within 2 years after SMILE. 5 Dr. Rostov said her SMILE enhancement rate was initially 3.4%, but after adding 10% to her nomograms, it's now much less. Dr. Rivers said he hasn't used a nomogram and has an enhance- ment rate of 0.2%. Looking at his own enhancement rates from about 500 LASIK cases and 500 SMILE cases over a year, Dr. Wiley said the SMILE enhancement rate was 2% and LASIK was 4%. "We had 20 LASIK enhancements versus nine SMILE, so 10 times $15,000 a day. That's $150,000 savings," Dr. Wiley said. Options when enhancement is needed If an enhancement is needed after a primary SMILE procedure, Dr. Wiley said there are several options that don't carry risk for epithelial ingrowth, which can occur with late LASIK flap lifts. "You've got the same options you would for a virgin eye," he said. "You can do PRK. You can do side cut only. You can do thin-flap LASIK or thick-flap LASIK." PRK If the patient elected for SMILE because they wanted to avoid a LASIK flap, PRK is the best option for enhancement in this case, Dr. Wiley said. "You don't want to offer a flap proce- dure when someone sought you out just for avoiding that, so that's something to keep in mind," he said. PRK is an option when the final pachymetry is more than 350 microns. Potential disadvantages of PRK as an enhancement include pain, haze, visual recovery, less predictability in hyperopic treatments, and epithelial remodeling leading to hyperopic overcorrection. Side cut only This option converts the SMILE cap into a LASIK-like flap. Using flap software, Dr. Wiley described how to start from the periphery, come into the center to the cap, and break suction. From there a side cut allows the surgeon to lift the flap. The flap diameter is limited by the original cap diameter, making this enhancement option for 6-mm, low-myopic corrections. It's not suitable for hyperopic or topog- raphy-guided corrections, which require a larger zone. The flap also has to be as thick as the cap (≤120 microns). Thin-flap LASIK If you don't want to do side cut only, Dr. Wiley said you can create a flap within the SMILE cap itself (a SMILE cap below LASIK). This option is more superficial than a side cut and has less of a biome- chanical effect. Dr. Wiley said you need to measure cap depth with OCT or ultrasound to ensure your flap stays within the cap. He said you should be at least 40 microns away from the thickness of the cap. The thinnest flap the VisuMax can create is 80 microns, so the SMILE cap needs to be at least 120 microns. Overall, Dr. Wiley said all of these are great options for the rare enhancement that might be needed with SMILE. References 1. Reinstein DZ, et al. Corneal sensitivity after small-inci- sion lenticule extraction and laser in situ keratomileusis. J Cataract Refract Surg. 2015;41:1580–1587. 2. Wang D, et al. Differences in the corneal biomechan- ical changes after SMILE and LASIK. J Refract Surg. 2014;30:702–707. 3. Wu D, et al. Corneal biomechanical effects: small-inci- sion lenticule extraction versus femtosecond laser-as- sisted laser in situ keratomileusis. J Cataract Refract Surg. 2014;40:954–962. 4. Chen M, et al. Comparison of biomechanical effects of small incision lenticule extraction and laser-assisted subepithelial keratomileusis. Acta Ophthalmol. 2016;94:e586–e591. 5. Liu YC. Enhancement after small-incision lenticule extraction: incidence, risk factors, and outcomes. Ophthalmol. 2017;124:813–821. Dr. Goel practices at Goel Vision in Baltimore, Maryland. He can be contacted at sonny.goel@gmail.com. Dr. Liu practices at IQ Laser Vision in Los Angeles, California. She can be contacted at drliu@iqlaservision.com. Dr. Rivers practices at Envue Eye and Laser Center in National Harbor, Maryland. He can be contacted at brivers2020@gmail. com. The views expressed in his presenta- tion are those of the authors and do not necessarily reflect the official policy or posi- tion of Belvoir Hospital, the Defense Health Agency, the Department of Defense (DoD) or the U.S. Government. Discussion of any commercial products within this presen- tation does not create or imply a Federal/ DoD endorsement. Dr. Rostov practices at Northwest Eye Sur- geons in Seattle, Washington. She can be contacted at audreyrostov@gmail.com. Dr. Wiley is the medical director of the Cleveland Eye Clinic in Cleveland, Ohio. He can be contacted at drwiley@ clevelandeyeclinic.com. The physicians have financial interests with Carl Zeiss Meditec. "Any enhancement that you have is going to cost you money. It's not just the cost of the enhancement itself, but it's that loss of referrals or loss of confidence, so it's expensive." —William Wiley, MD

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