First Experience in Small Incision Lenticule Extraction with the Femto LDV Z8 and Lenticule Evaluation Using Scanning Electron Microscopy

PURPOSE: To evaluate the specifications and technique properties of the new Femto LDV Z8 in creating intrastromal refractive lenticules during small incision lenticule extraction (SMILE). METHODS: Six enucleated porcine eyeballs were equally divided into two groups (Femto LDV Z8 or VisuMax) and were randomly assigned to three experienced refractive surgeons who performed SMILE on each group. Five intraoperative time parameters and surgeons' satisfaction on the surgical procedure were compared between two groups. Postoperatively, the roughness of the lenticule surfaces and the irregularity of edges were observed by scanning electron microscopy (SEM) and were also compared between the two groups. RESULTS: Longer time on suction peak pressure, total laser application, and total surgery were spent in the Femto LDV Z8 group as compared with the VisuMax group. The Femto LDV Z8 group applied OCT scanning and offsetting before performing the laser procedure, which expended more time for these crucial steps. The widest range of surgeons' satisfaction scores was found in the step of lenticule interface identification of the Femto LDV Z8 group. The roughness scores of the anterior and posterior lenticule surfaces were statistically less in the Femto LDV Z8 group than in the VisuMax group (anterior, ×180, p=0.039; anterior, ×250, p=0.337; posterior, ×180, p=0.006; and posterior, ×250, p=0.007). CONCLUSIONS: Femto LDV Z8 showed promising performances as a novel SMILE equipment for the correction of myopia. It has special and unique features for SMILE procedures, which need more learning and researching processes. With its low-energy high-frequency nJ-level laser system, the Femto LDV Z8 provided smoother lenticule surface than VisuMax.