The evolution of corneal and refractive surgery with the femtosecond laser.

The use of femtosecond lasers has created an evolution in modern corneal and refractive surgery. With accuracy, safety, and repeatability, eye surgeons can utilize the femtosecond laser in almost all anterior refractive procedures; laser in situ keratomileusis (LASIK), small incision lenticule extraction (SMILE), penetrating keratoplasty (PKP), insertion of intracorneal ring segments, anterior and posterior lamellar keratoplasty (Deep anterior lamellar keratoplasty (DALK) and Descemet's stripping endothelial keratoplasty (DSEK)), insertion of corneal inlays and cataract surgery. As the technology matures, it will push surgical limits and open new avenues for ophthalmic intervention in areas not yet explored. As we witness the transition from femto-LASIK to femto-cataract surgery it becomes obvious that this innovation is here to stay. This article presents some of the most relevant advances of femtosecond lasers to modern corneal and refractive surgery.

Laser in situ keratomileusis flap-thickness predictability with a pendular microkeratome.

PURPOSE: To assess flap-thickness predictability with a pendular microkeratome (130 µm head). SETTING: Eye Institute of Thrace, Democritus University of Thrace, Alexandroupolis, Greece. DESIGN: Clinical trials. METHODS: The study comprised 263 eyes (132 patients). Laser in situ keratomileusis was performed using the 130 µm head of the Carriazo pendular microkeratome; right eyes were treated first. Ultrasound pachymetry and topography were used for central corneal thickness (CCT) and keratometry (K) measurements. Evaluation included flap thickness, flap diameter, and flap shape. RESULTS: The mean flap thickness was 125 µm ± 22 (SD) (range 74 to 187 µm) in right eyes and 112 ± 21 µm (range 61 to 190 µm) in left eyes. Flap thickness was significantly correlated with preoperative CCT (r = 0.271; P<.001) but not with K values or the manifest refraction spherical equivalent (P>.15). Right eyes had thicker flaps than left eyes (P<.001); both were significantly below the 130 µm head thickness (mean flap thickness 119.2 ± 22.8 µm; P<.001). The mean achieved flap diameter was 9.2 mm using the 9.0 ring and 9.8 mm using the 10.0 mm ring. Flap-thickness stabilization and convergence between right eyes and left eyes occurred after 100 consecutive flap cuts. CONCLUSIONS: Flap-thickness predictability was influenced by preoperative CCT only. All cuts were significantly thinner than the head thickness regardless of the suction ring size. Second surgical eyes had thinner flaps, possibly from blade deterioration from the first cut. Approximately 100 flaps were required as a learning curve.

Corneal flap assessment with Rondo microkeratome in laser in situ keratomileusis.

PURPOSE: To assess the accuracy of flap thickness in laser in situ keratomileusis (LASIK) with Rondo, Wavelight AG microkeratome and to examine factors that can influence flap thickness (FT). SETTING: The study took place at the Laser & Ophthalmos Eye Clinic, Thessaloniki, Greece. MATERIAL AND METHODS: Three hundred and sixty eyes from 180 patients underwent LASIK with Rondo microkeratome. Three surgeons (A, B and C) performed all surgeries with no previous experience of Rondo microkeratome. All patients were treated with the 130 µm plate. Central corneal thickness (CCT) and stromal bed thickness were measured by Scheimpflug and ultrasound pachymetry. Right eye (OD) was treated first. RESULTS: Mean FT for OD: 120 ± 19 µm (range 69-158 µm); for left eye (OS): 106 ± 17 µm (range 70-147 µm). Flaps in OD were significantly thicker than in OS (p < 0.001). FT was significantly correlated to the keratometric reading (K): r = 0.121; p = 0.02. No correlation was found between FT and CCT or between FT and the attempted refractive correction (SE) (p > 0.14). Mean FT was significantly lower than the manufacturer's 130 µm specification (Mean FT = 113 ± 19 µm; p < 0.001). FT between surgeons A, B and C was significantly different (analysis of variance between surgeons; p < 0.001). Scheimpflug and ultrasound CCT measurements were significantly correlated (r = 0.921; p < 0.001) with ultrasound measuring an average 4.5 µm higher than Scheimpflug (CCT (Oculyzer) = 553.96 ± 27 µm; CCT (Ultrasound) = 558.45 ± 28 µm). Mean flap diameter was 9.2 ± 0.2 mm. CONCLUSIONS: FT with Rondo microkeratome was significantly influenced by the mean preoperative K reading. First treated eye was significantly thicker than the fellow left eye, while both were significantly lower than the recommended 130 µm thickness. Gaining basic experience of Rondo microkeratome required an average of 90 flaps/surgeon.