TOUCH MEDICAL MEDIA 24 Practice Pearl Refractive Surgery Print Publication Date: 13 August 2018 Practice Pearls for ReLEx SMILE in 2018 Dan Z Reinstein London Vision Clinic, London, UK; Department of Ophthalmology, Columbia University Medical Center, New York, NY, US; Centre Hospitalier National d’Ophtalmologie, Paris, France; Biomedical Science Research Institute, University of Ulster, Coleraine, UK S mall incision lenticule extraction (SMILE) provides another option in the treatment of refractive error. An improvement in docking and centration, globe stabilisation and cap interface recovery technique can provide both the surgeon and patient with a chance of a smoother process, better outcome and fewer complications. Keywords Small incision lenticule extraction, SMILE, centration, recovery technique, docking, cap interface Disclosure: Dan Z Reinstein is a consultant for Carl Zeiss Meditec (Jena, Germany), has a proprietary interest in the Artemis technology (ArcScan Inc, Morrison, Colorado) and is an author of patents related to VHF digital ultrasound administered by the Cornell Center for Technology Enterprise and Commercialization (CCTEC), Ithaca, NY, US. Review Process: This article is a short educational piece and has not been submitted to external peer reviewers but was reviewed by the editorial board for accuracy before publication. Authorship: All named authors meet the International Committee of Medical Journal Editors (ICMJE) criteria for authorship of this manuscript, take responsibility for the integrity of the work as a whole, and have given fnal approval to the version to be published. Open Access: This article is published under the Creative Commons Attribution Noncommercial License, which permits any noncommercial use, distribution, adaptation, and reproduction provided the original author(s) and source are given appropriate credit. © The Authors 2018. Received: 18 May 2018  Published Online: 13 August 2018 Citation: European Ophthalmic Review. 2018;12(1):24–5 Corresponding Author: Dan Z Reinstein, London Vision Clinic, 138 Harley Street, London W1G 7LA, UK. E: dzr@londonvisionclinic.com Support: No funding was received in the publication of this article. Small incision lenticule extraction (SMILE) has been gaining major traction since it was fully commercialised in 2012, with more than 1.3 million procedures performed to date worldwide. Our first SMILE experiences began in 2010 during its development and since 2012 we have offered this routinely to our patients. On completion of our first 4,000 SMILE cases we performed a full data analysis of our evolving surgical technique, outcomes and complications which formed the basis for our recently published textbook ‘The Surgeon’s Guide to SMILE: Small Incision Lenticule Extraction’. 1 Over time we developed a fully standardised SMILE technique and a number of pearls that will help every physician ranging from a beginning novice to an expert who has performed thousands of cases. Here we share some insights that can improve outcomes as well as minimise and manage complications. Pearl 1 – Docking and centration In SMILE, the alignment of the refractive lenticule is effectively auto-centred by the patient fixating coaxially on a fixation light prior to suction being applied, resulting in lenticule formation centred on the corneal vertex of the coaxially fixating eye. No eye tracker is required during femtosecond cutting in SMILE as the eye is immobilised, although this means that if suction is applied incorrectly the treatment zone will be decentred. To help this process, we prepare a printout (Figure 1), including the topography eye image and the Hirschberg test, for the surgeon to compare to the intraoperative appearance. 2 We find the topography eye image is the most useful reference for angle kappa and have developed a display that includes visual cues to quantify the magnitude and direction of any angle kappa (created by importing the Atlas image into PowerPoint and adding crosshairs; this template is available to download from www.londonvisionclinic.com/SMILECentrationTemplate). The docking process only takes a few seconds, so it is important for the surgeon to be able to immediately see, at a glance, the expected position of the reflex. However, the Atlas eye image is not infallible; for example, the patient may not have been coaxially fixating during acquisition, and the pupil diameter during treatment is usually slightly smaller than on the eye image, so these need to be mentally accounted for. With that being said, this is an easy double check to make sure the treatment is centred properly. Pearl 2 – Globe stabilisation during lenticule separation Many SMILE surgeons choose not to use an instrument to control the position of the eye during lenticule separation and many thousands of SMILE procedures have been done in this way. There is no reason to say that an immobilising instrument must be used, but the weight of advantages is with immobilisation and surgeon control of the globe. With the eye controlled by the surgeon, the force of the lenticule separation is controlled, whereas with a free-floating globe the eye will move around in the direction of the force applied with a force that is determined by the patient’s extraocular muscle status. The use of a toothed-forceps at the limbus gripping down to Tenon’s layer also allows the surgeon to apply counterforce against the lenticule separator. Other disadvantages of allowing the globe to move freely with a single-instrument separation technique include the eye being shifted outside the surgical field of the microscope, producing a limited view or an increase in dissection time while the surgeon corrects the patient’s fixation. DOI: https://doi.org/10.17925/EOR.2018.12.1.24