الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Femtosecond lasers were first introduced into refractive surgery, the ultimate goal has been to create an intrastromallenticule that can then be removed in one piece manually, thereby circumventing the need for incremental photoablation by an excimer laser. A precursor to modern ReLEx was first described in 1996 using a picosecond laser to generate an intrastromallenticule that was removed manually after lifting the flap.
However significant manual dissection was required leading to an irregular surface. The switch to femtosecond improved the precision.
Following the introduction of the VisuMax femtosecond laser (Carl Zeiss Meditec, Jena,Germany) in 2007the intrastromallenticule method was reintroduced in a procedure called Femtosecond Lenticule Extraction (FLEx).
The refractive results were similar to those observed in LASIK, but visual recovery time was longer due to the lack of optimization in energy parameters and scan modes; further refinements have led to much improved visual recovery times.
Following the successful implementation of FLEx, a new procedure called Small Incision Lenticule Extraction (SMILE) was developed. This procedure involves passing a dissector through a small 2-3mm incision to separate the lenticular interfaces and allow the lenticule to be removed, thus eliminating the need to create a flap. The results of the first prospective trials of SMILE have been reported and there are now more than 50 surgeons routinely performing this procedure worldwide.
ReLEx is available in two options, ReLEx flex and ReLEx smile. ReLEx flex is designed to preserve biomechanical stability and achieve perfect positioning of the lenticule in a flap-like access cut Meanwhile, ReLEx was advanced to the latest procedure ReLEx smile. Additionally to the known advantages, this new minimally invasive treatment ReLEx smile is characterized by extracting the lenticule through a small incision. Thus, ReLEx smile eliminates the need for cutting a flap.
Advantages of lenticule extraction include uniform flap thickness, induccion barely any astigmatismand more accurate and repeatable tissue removal independent of prescription treated, increased biomechanical integrity of the postoperative cornea and eduction in postoperative dry eye symptoms and recovery.
Disadvantages of lenticule extraction include transient enhanced visibility of the interface was apparent during the slit-lamp examination.
However, may be there is a possible drawback of the SMILE procedure is an inability for in situ enhancement. Currently, SMILE-treated eyes would either require an add-on surface ablation or a surgical opening (with femtosecond laser or manually) of the side cut incisions, thus creating a flap, for enhancement purposes. .