SMALL INCISION LENTICULE EXTRACTON (SMILE) SMILE ; is a relatively new refractive procedure designed to treat a multitude of refractive errors such as myopia, hyperopia, presbyopia, and astigmatism. The procedure involves using a femtosecond laser to create a corneal lenticule which is extracted whole through a small incision without the use of an excimer laser. During the SMILE procedure, the patient is raised to the contact glass of the femtosecond laser and suction ports are activated to keep the patient's eye fixated in the correct position while the lenticule is created. The lower interface of the intrastromal lenticule is created first (using an out-to-in direction with the laser to maximize the time without blurring the patient’s central vision), followed by the upper interface of the lenticule (using an in-to-out direction), known as the cap, and finally a 2–3 mm tunnel incision (usually supero-temporal) that links the cap interface to the corneal surface. To avoid any undesirable effects in the cornea such as haziness, the two interfaces (lower and upper) are created from the endothelial side of the cornea to the epithelial side. The patient is then moved to the surgical microscope for the lenticule separation and extraction part of the procedure. The layers of the lenticule are outlined and the lenticule is removed from the cornea using a pair of retinal micro-forceps, or can be extracted directly from within the pocket with the latest versions of the lenticule stripper, one of many instruments being developed for the SMILE procedure specifically. When planning the treatment, the following parameters can be selected by the surgeon: cap thickness, cap diameter, cap sidecut angle, refractive correction, lenticule diameter (optical zone), lenticule sidecut angle, and the minimum lenticule thickness (so that the lower lenticule interface can be easily differentiated from the upper interface). CONCLUSIONS : The SMILE procedure, while still in its early stages, seems to be a promising alternative to LASIK in some cases. Given its flapless technique and results that appear to be similar to LASIK, it may offer the same correctional abilities with the potential benefits of faster recovery of post-op dry eye, quicker reinnervation of corneal nerves, and biomechanical advantages. After clinical trials are completed for SMILE and pending its approval, this procedure may be an upcoming option for some patients, due to its minimally invasive technique and promising outcomes.
Op.Dr.Ahmet UMAY Bristol University Ophtalmology Section References : Eyewiki.aao.org Small incision lenticule extraction (SMILE) history, fundamentals of a new refractive surgery technique and clinical outcomes. Eye and Vision Innovative SMILE Procedure from ZEISS Successfully Performed on More than 80,000 Eyes." Innovative SMILE Procedure from ZEISS. Mehta JS (2014) New Instruments for Lenticule Extraction in Small Incision Lenticule Extraction (SMILE). Refractive lenticule extraction: Transition and comparison of 3 surgical techniques Journal of Cataract & Refractive Surgery , Dry Eye Disease after Refractive
Surgery: Comparative Outcomes of Small Incision Lenticule Extractionnversus LASIK, Ophthalmology.
