Visumax

A VisuMax (Carl Zeiss Meditec) femtosecond laser platform was used for all surgical procedures. Surgery was performed as described by a previous study and was done by the same experienced surgeon [18 (link)]. The suction time lasted for 24 seconds during the lenticule creation. Postoperatively, in addition to the regular topical antibiotics (ofloxacin ophthalmic solution 0.5%; Santen Pharmaceutical Co., Ltd.) and artificial tears (sodium hyaluronate eye drops 0.3%; Santen Pharmaceutical Co., Ltd.), topical steroids (fluorometholone 0.1%; Santen Pharmaceutical Co., Ltd.) were initially administered 6 times a day and tapered off over 20 days.

The same surgeon (YL) performed all surgeries. The SMILE procedure was done under topical anesthesia using the VisuMax® 500 kHz femtolaser system (Carl Zeiss Meditec, Jena, Germany). The refractive target was to achieve emmetropia. The following parameters were used: cap thickness, 110–120 μm; cap diameter, 7.0–7.5 mm; lenticule diameter, 6.0–6.5 mm with a transition zone of 0.1 mm; cut energy, 135 nJ; spot distance, 4.5 μm for the lenticule and 2.0 μm for its border; and the side cut incision, 2 mm at the 10 o'clock position of the cornea. After removing the refractive lenticule, 0.22% riboflavin with saline (VibeX Xtra, Avedro) was instilled through the small incision into the corneal pocket and allowed for a soak time of 90 seconds. Then, the photosensitizer was utterly washed out from the pocket using a balanced saline solution. This was followed by an ultraviolet A (UVA) irradiation using the Avedro's (Avedro Inc.) corneal cross-linking system at 30 mW/cm² for 90 seconds (total energy: 2.7 J/cm²). No intraoperative complications were recorded.
Postoperative treatments included topical administration of 0.5% levofloxacin (Cravit, Santen) four times a day for two weeks, 0.5% loteprednol etabonate ophthalmic suspension (Lotemax, Bausch & Lomb) four times a day in the first week, followed by tapering dosages for three weeks, and lubricants four times daily for three months.

In ReLEx SMILE procedure, a femtosecond laser system (Carl Zeiss Meditec AG VisuMax) with a repetition rate of 500 kHz was used to perform the whole surgical. The cap thickness set at 110 μm and the diameter was set 7.0~7.5 mm. The lenticule size was 6.2 ± 0.2 mm (range 6.0~6.5 mm) with no transition zone for spherical aberration and an 0.1 mm transition zone for astigmatism correction. A side-cut incision angle was set 90° and the side-cut incision was set at 2~4 mm. the ablation energy was 110~175 nJ. The ablation order was as follows: the posterior surface of the lenticule; the anterior surface of the lenticule; the side cut and the side-cut incision. The lenticule was then separated bluntly and removed with a forceps through the side-cut incision.

The surgical technique has been explained in detail elsewhere [2 (link)]. Briefly, a 500 kHz Visumax femtosecond laser (Carl Zeiss Meditec AG, Jena, Germany) was used; cap thickness ranged from 100 to 130 μm, cap diameter from 7.3 to 7.9 mm, and lenticule diameter from 6.0 to 7.0 mm with a transition zone of 0.0 to 0.1 mm. The laser cut energy index was between 25 and 34 and the spot spacing between 2.5 μm and 4.5 μm. Lenticule dissection was done with a blunt spatula, and the lenticule was extracted through a 30–40° opening at 12 o’clock. Patients were postoperative treated with tobramycin-dexamethasone q.i.d. tapered over 2 weeks.