Eyeworld

106 April 2016 EW REFRACTIVE SURGERY by Matt Young and Gloria Gamat EyeWorld Contributing Writers Study reports findings on the potential use of cryopreserved corneal lenticules in humans S ince small incision lent- icule extraction (SMILE) became clinically available in 2011, the procedure has turned into a compel- ling LASIK alternative for refractive surgeons. SMILE's biggest attraction to surgeons and patients alike can be attributed to the fact that it address- es postoperative issues related to laser-assisted in situ keratomileusis (LASIK). From dry eye to astigmatism, common side effects or limitations of LASIK may be minimized by SMILE, as reported by various inves- tigators worldwide in recent years. Today, according to recent data from Carl Zeiss Meditec (Jena, Ger- many), SMILE is being regularly per- formed by more than 700 surgeons, and there are more than 300,000 SMILE procedures already performed worldwide. With this many procedures, what could refractive surgeons do with all those extracted lenticules? Lenticular implantation technique In the December 2014 issue of Cornea, Ganesh and colleagues 1 reported their findings on the po- tential use of cryopreserved corneal lenticules in humans, a novel appli- cation of SMILE-extracted lenticules. "With the increasing number of eyes undergoing ReLEx SMILE for myopia, and thus, the extracted lenticules as a byproduct, it may be a novel idea to preserve these lenticules on a long-term basis using cryopreservation for potential future use and research," the investigators stated. Novel application of SMILE-extracted lenticules continued on page 108 Postoperative clinical photos post-FILI for +6.5 D hyperopia, (A) at day 15 and (B) at 3 months, showing clear and well-centered lenticule with no shift in position over time. (C) AS-OCT picture of the same eye at 3 months, showing stable position of the lenticule. Source: Sheetal Brar, MBBS "Lenticules from myopic pa- tients undergoing ReLEx SMILE at our center were cryopreserved for use in heterologous individuals to treat hyperopia using a tissue addi- tion technique," said Sri Ganesh, MD, chairperson, managing director, and medical director, Nethradhama Super Specialty Eye Hospital, Banga- lore, India. To implant the donor lenticule, a femtosecond laser intrastromal lenticular implantation (FILI) tech- nique was used. During the course of the proce- dure, the VisuMax femtosecond laser system (Carl Zeiss Meditec) was used to create a 7.5 mm diameter pocket at a depth of 160 mm and with a 4 mm superior incision. "A depth of 160 mm was chosen for implantation in all patients due to uncertainty in refractive out- comes, the novelty of the nomo- grams, and so the surgeon could have adequate tissue in the cap for later enhancement with surface ab- lation if required," Dr. Ganesh said. The use of a femtosecond laser with the FILI technique, Dr. Ganesh and colleagues emphasized, over- comes the problems encountered with epikeratophakia when treating aphakia in the old days. A femto- second laser enables the creation of precise lenticules and incisions at an accurate depth, which was not possible with the old concept. "Tissue addition may be con- sidered as a resurgence of Barraquer principles and techniques of using cryolathed corneal tissue for man- agement of refractive errors," said Sheetal Brar, MS, study co-author and consultant, phaco and refractive department, and research coordina- tor, Nethradhama Superspeciality Eye Hospital. The older techniques, Dr. Brar noted, could not become popular due to unpredictability of results A B C

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