EyeWorld Asia-Pacific June 2016 Issue

June 2016 30 EWAP SECONDARY FEATURE by Sri Ganesh, MD SMILE: Personal experience T he ReLEx small incision lenticule extraction (SMILE) technique of refractive corneal surgery is a relatively new procedure and there is a lot of excitement with quite a few ophthalmologists actively adopting this procedure. LASIK is a mature technology and gives good results but the refractive market worldwide has stagnated or declined due to some bad press and dissatisfied patients. SMILE offers a new avenue for attracting patients and increasing the refractive market. From the patients’ perspective, SMILE is very attractive as it is a painless, short, and minimally invasive procedure. There are almost no special postoperative precautions or care and patients can go back to their normal activities including sports the very next day. Various studies have shown that quality of vision, dry eye status, and refractive stability are very good after 3 months. Patients would perceive it as an easier and safer procedure. Surgeons are looking up to this procedure for the various benefits it offers over LASIK, being a flapless procedure. There is less induced spherical aberration than wavefront-optimized LASIK as tissue is removed en-block from the periphery without the cosine effect and reduced fluence of excimer lasers. There are fewer variables such as environmental factors and energy variation when compared to an excimer laser which may result in more predictable results. There is less long-term dry eye with SMILE as compared to LASIK due to better preservation of the subbasal epithelial plexus. The potential benefit of better corneal biomechanics may lead to reduced incidence of corneal ectasia and the ability to treat higher refractive errors safely. The SMILE procedure is still in its infancy and has to be refined, but many comparative studies with wavefront-optimized femtoLASIK show that the refractive results and safety may be comparable or better. There is still a lot of development that has to take place with the lenticule extraction technique. Software for treating hyperopia and mixed astigmatism is being developed and early results from clinical trial sites indicate good success. Centration in the SMILE treatment is dependent on patient fixation and future hardware for confirming good centration would improve outcomes. Also, automatic cyclotorsion compensation for astigmatism has to be introduced. The ability to treat irregular or aberrated corneas with a link to a topographer or aberrometry is still a long way off. The lenticule extraction technique has shown very good stability over time when compare to LASIK or PRK especially for higher refractive errors with very low enhancement rates. Currently, the options for enhancement are either LASIK by converting the cap into a flap using a special circle software or surface ablation. There is a possibility of doing re-SMILE for enhancement and I have had some personal experience, and so also a few other surgeons but this is Sri Ganesh off-label and not promoted by the company (Carl Zeiss Meditec, Jena, Germany). SMILE is a surgeon-based procedure with a learning curve which may be steeper than LASIK or PRK. Optimizing energy levels, learning to dock and center the eye are important and can be mastered initially by using the VisuMax laser (Zeiss) to create flaps. Identifying the correct tissue planes and easy dissection with minimal tissue distortion improves immediate postoperative recovery. The learning curve with SMILE can be reduced by observation and proper training. There can be complications like suction loss, retained lenticule, lenticule tear which are unique to this procedure and also difficult dissection due to suboptimal fluence levels which have to be handled properly to ensure smooth outcomes. The future for small incision lenticule extraction appears quite bright and as advances in technology progress, it might replace LASIK in the near future. Editors’ note: Dr. Sri Ganesh is a consultant for Carl Zeiss Meditec.