Femtosecond laser-assisted stromal lenticule addition keratoplasty for the treatment of advanced keratoconus: A preliminary study

PURPOSE: To investigate the in vivo effect of a novel femtosecond laser-assisted procedure termed stromal lenticule addition keratoplasty for advanced keratoconus. METHODS: Ten patients with stage III and IV stable keratoconus were included. Negative meniscus-shaped stromal lenticules were produced from corneoscleral eye bank buttons with a refractive lenticule extraction procedure with a 500-kHz VisuMax femtosecond laser (Carl Zeiss Meditec, Jena, Germany). Recipient corneas underwent a modified femtosecond laser flap-cut procedure to produce an intrastromal pocket and lenticules were implanted. Patients were followed up for 6 months after surgery with determination of uncorrected (UDVA) and corrected (CDVA) distance visual acuity, subjective refraction and topographic corneal curvature changes, anterior segment optical coherence tomography (AS-OCT), and in vivo confocal microscopy. RESULTS: Comparison of preoperative and 6-month postoperative UDVA and CDVA showed statistically significant improvements (P = .024 and .007, respectively) from 1.58 ± 0.36 to 1.22 ± 0.37 and from 1.07 ± 0.17 to 0.70 ± 0.23 logMAR. Eight of 10 eyes showed an improvement in UDVA (P < .001) that ranged between one and three lines, whereas all but one eye presented improved CDVA. Corneal topography documented a decrease between preoperative and 6-month postoperative anterior mean curvature (AVG-K at 3 mm) and anterior Q values (P = .005). AS-OCT showed a significant increase in thickness of the central and mid-peripheral cornea produced by the lenticule implantation (P = .005). CONCLUSIONS: The stromal lenticule addition keratoplasty procedure was clinically efficient in improving the corneal shape and vision in patients with keratoconus. Negative meniscus-shaped lenticule addition induced a flattening of the cone while increasing corneal thickness.