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Theresa M. Rueckl, Alois K. Dexl, Veronika Reischl, Perry S. Binder, Günther Grabner; Intrastromal Arcuate Keratotomy using a Femtosecond Laser. Invest. Ophthalmol. Vis. Sci. 2011;52(14):5747.
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To demonstrate the initial results of an intrastromal arcuate keratotomy (ISAK) performed with an IntraLase femtosecond (fs) laser (iFS, AMO, Ca.)
In this prospective single center study, two groups of patients with astigmatism (naturally occurring or post cataract surgery) were treated with the fs-laser performing arcuate cuts completely placed within the corneal stroma on the steep axis. Depending on the amount of astigmatism (treatment goal: 0,75 to 3,0 diopters) four different treatment patterns (with selection of zone diameter, side cut angle and a width of the incision according to the pachymetry values) were used. This laser system can be programmed to predictably deliver the preselected cut patterns. A marking of the steep axis was done using the Keratron Scout, an intraoperative videokeratoscope, and an ultrasound-pachymetry was performed in four quadrants immediately preceding the laser treatment. Patients were followed for a minimum of three months after surgery and keratrometric changes were assessed with the Pentacam HR, the Keratron Scout and a wavefront analyser.
To date 15 eyes were treated with this method; 13 patients showing naturally occurring astigmatism, most of them selected prior to cataract surgery, two additional patients presented with an astigmatism following cataract surgery. No perforations occurred with all incisions being placed at the planned location. They were barely visible by slit-lamp examination at the first postoperative day, but could be detected with the OCT (Visante, CZM, Germany). The reduction of astigmatism was found to be between 0.25 and 2.5 diopters with a high stability of the refractive error and corneal topography over time. The amount of induced change was highly dependable on the cut angle (between 30 and 150 degrees). Endothelial cell count was found to be unchanged as compared with preoperative values.Patient's satisfaction was generally very high.
The iFS-laser allows the creation of precise, purely intrastromal incision patterns that are not readily achievable by standard diamond blade techniques. These preliminary outcomes indicate an excellent safety profile, the possibility of highly precise pattern placement and very rapid recovery and stability of vision.
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