| Abstract |
The femtosecond laser produces ultrashort pulses of 10-15 sec resulting in vaporation of tissue at focal point without significant thermal effects on surrounding tissues. Its applications in refractive surgery include creating of corneal flap in LASIK, the astigmatism correction with astigmatic keratotomy and wedge resections with very high accuracy, the creation of intracorneal tunnels for the insertion of intracorneal rings to correct myopia, keratoconus and ectasia, the creation of intrastromal pockets for the insertion of intrastromal inlays to correct presbyopia, the myopia correction method ReLEx, the IntraCOR method for the correction of presbyopia, the corneal biopsy, corneal transplantation, cataract surgery and the correction of presbyopia by increasing the elasticity of the crystalline lens.
The introduction of femtosecond laser has improved the accuracy and safety of flap creation. The predictability of the thickness of the flap and the ability to create uniform flaps has minimized the risk of complications compared to traditional manual keratotomy. Regarding intracorneal rings and inlays, as compared to manual techniques, the femtosecond laser is making tunnel and pocket faster, easier and more reproducible and allows precise dimensions (width, depth and diameter). The femtosecond laser astigmatic keratotomy and wedge resections correct the residual astigmatism while the method ReLEx (FLEx and SMILE) allows correction of myopia using only one femtosecond laser since this methodology consists in removing part (microlenses) of the corneal stroma without conducting keratomileusis with an eximer laser. Biopsy of cornea becomes more accurate and safe way, with the results to be representative of the actual status of the tissue, especially in cases of severe disease. The femtosecond laser-assisted corneal surgery improves the results of traditional transplantation, both in performance penetrating keratoplasty and in - targeting diseases - lamellar keratoplasty. The femtosecond laser is capable of reliable corneal incisions of both the donor and recipient and used to divide the corneal donor tissue in the anterior and posterior layer, for use in partial thickness lamellar (DALK) or endothelial keratoplasty (DSAEK). The effectiveness of this technique lies in transplant preservation of the cornea portion of the receiver that is healthy (endothelium) which reduces the risk of graft rejection, bleeding and infection within the eye. Endothelial keratoplasty DSAEK replaces only the
diseased endothelium with a graft consisting of a thin layer of posterior stroma, Descemet's membrane and endothelium. Finally, the femtosecond laser assisted cataract surgery (FLAC) is carried out on three critical steps: the laser-assisted corneal section, capsulotomy and lens fragmentation.
Although the Femtosecond (FS) laser offers several advantages over conventional lasers, such as high penetration, short duration pulses and micro-precision, predictability, repeatability and safety, some issues remain unresolved. Despite the proven and indisputable advantages of femtosecond lasers, it is necessary to conduct more studies to clarify the optimal utilization. However, the increasing capabilities and applications of femtosecond laser as well as the continuing improvement of this technology and techniques will accrete more surgeons in near future. This thesis is a literature review of femtosecond laser applications in refractive surgery.
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