The treatment pack
During this period of time in 2005, a series of studies by Blum and Sekundo (unpublished data) on animals, blind and amblyopic eyes, underwent a new refractive procedure, which no longer required an excimer laser (Fig. 4.2). The procedure was called femtosecond lenticule extraction (FLEx) in order to distinguish it from other known refractive procedures. In autumn of 2006, during the American Academy of Ophthalmology Meeting in Las Vegas/USA, Sekundo and Blum presented the very first ten cases of corneal refractive correction using a prototype of the VisuMax® femtosecond laser. The first peer-reviewed article was published by Sekundo et al. in 2008 . Animation images of the procedure reproduced from the first award-winning surgical video shown by Sekundo and Blum at the 2008 ASCRS Meeting in Chicago are summarized in Fig. 4.3.
A photograph from the first animal experiments testing femtosecond lenticule extraction
A schematic drawing of the FLEx procedure. The VisuMax® femtosecond laser system cuts the back of the refractive lenticule (a) followed by its front surface incision (b) followed by a vertical incision leaving an arc of 50° untouched (hinge). The final step is performed manually, with the flap beeing lifted (c) with the spatula and the lenticule removed manually using forceps (d). The flap is then repositioned (e)
A cohort of fully seeing eyes treated for myopia and myopic astigmatism followed this very first report. 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. These eyes were followed up for 6 months and – on a voluntary basis – for 12 months [20, 21]. Meanwhile, 5-year results of this initial cohort have been published .
In this first larger series, the intended flap thickness varied between 110 and 160 μm; the flap diameter was chosen between 7.0 and 8.5 mm. In all 108 cases, a superior hinge, 50° in chord length, was left. The lenticule diameter varied between 6.0 and 7.3 mm according to patient’s scotopic pupil diameter. No nomograms were available at the beginning, and a special equation (Patent No. DE 102006053120 A1) based on Mannerlyn’s formula was used to calculate the geometry and the thickness of the refractive lenticule. The postoperative regimen consisted of preservative-free antibiotic, steroid, and hyaluronic acid lubricating drops four times per day each for 1 week. Keeping in mind that this first prospective clinical study started without a nomogram, the results of 98.1 % of eyes within 1 D of refractive target were satisfactory and exceeded our expectations.
Shah was the third surgeon in the world who took up the ReLEx technique and significantly contributed to its development in the early phase of this procedure. Her main achievement was not only to optimize laser settings for the 200 kHz machine used at this stage of development in a substantial number of patients but also to realize that also the laser scan (or cut) direction matters .
Following the successful implementation of FLEx, the next aim was to further develop a surgical procedure in which a flap no longer was necessary. 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 then removed through the incision (Fig. 4.4). 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. The first surgical video of SMILE was shown during the Cataratta refractiva in Milano in 2009. However, it took another 3 years till peer-reviewed publications appeared in the scientific literature [24, 25]. The first larger series of eyes operated with the SMILE technique was published by Sekundo and Blum et al. and, unlike in today’s SMILE, was carried out through two opposite entering incisions, 4 mm each . A total of 91 eyes clearly demonstrated the “prove of principle,” and the encouraging results motivated a number of researchers to test the new surgical technique [25–27]. This resulted in a variety of smaller changes in surgical technique, but the main elements remained unchanged: the laser first created the lower interface, followed by the upper interface of the lenticule either using an out-to-in direction or using an in-to-out direction. Shah was the first surgeon to use a single-entering incision , and it was also her who systematically worked toward very small incision used today.
A schematic drawing oft he SMILE procedure. The VisuMax femtosecond laser system cuts the lenticule (a) followed by a small incision (b). The lenticule is removed through the small insision (c)
Although the refractive results were good in the first study (very close to those observed in LASIK), visual recovery time was slightly longer. The effect of different scanning patters, optimization of energy parameters, and spot-spacing settings led to much improved visual recovery times [23, 26, 28, 29]. Furthermore, a 500-kHz-laser was released and the precision of lenticule creation was improved [30, 31]. In terms of safety and complications, SMILE has also been shown to be quite outstanding . Meanwhile, first results are also available for the treatment of hyperopia (see Chap. 19). After 2010–2011, the technique became increasingly popular, and many outstanding surgeons joined the “SMILE community” improving the quality of this procedure step by step. It is a pleasure to have many of these surgeons as coauthors of this book sharing their view of the present and the future of “all-in-one” femtosecond laser surgery.