This very first report was followed by a cohort of fully seeing eyes treated for myopia. A total of 108 eyes had been recruited and treated from 56 patients with spherical myopia between −2 and −8.5 D and myopic astigmatism up to −6 D cyl. The eyes were followed up for 6 months and – on a voluntary basis – for 12 months [16, 17]. Meanwhile 5 year results were published [18].

The consequent improvement of the FLEx technique which requires a flap was the development of a flapless technique. A flapless technique would enable a mechanic stable cornea. FLEx turned out to be just one step towards developing a new technique without lifting the flap – made possible by continuous improvements in surgical performance, energy settings, and laser technology [19–21]. This procedure was named Small Incision Lenticule Extraction (SMILE): by passing a dissector through a small 2–3 mm incision the anterior and posterior lenticular interfaces are separated and the lenticule is than removed through the incision (Fig. 2.2a–c). This eliminates the need to create a flap and the cornea above the upper interface of the lenticule is now referred to as the cap.

First results of this minimally invasive procedure have been published by our group in 2011 [22]. The potential advantages of this refined technique have encouraged a number of international groups to employ the newly developed 500 kHz femto second laser for refractive lenticule extraction [23–25]. In order to avoid confusion, the “all in one” femtosecond laser alone procedures have been patented by the manufacturer of the VisuMax laser as refractive lenticule extraction (ReLEx®) with two possible techniques: the ReLEx® flex and ReLEx® smile. Meanwhile the small incision lenticule extraction (SMILE) became a well-known term, which in our opinion will remain irrespective of the manufacturer of the laser.

The rapid increase in available clinical data has led to an ongoing discussion about the advantages and disadvantages of ReLEx femtosecond lenticule extraction [26–36]. We will now describe the technique in its different stages and its current clinical applications.