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    The femtosecond laser in everyday clinical use

    A first-hand account of the many treatment options available


    Mark Tomalla, MD
    The use of femtosecond lasers has significantly increased in recent years, with many surgeons preferring this newer tool to traditional surgical methods.

    Figure 1: Femtec femtosecond laser.
    Here, Mark Tomalla, MD tells us of his experience with the femtosecond laser, Femtec (20/10 Perfect Vision, Heidelberg, Germany) (Figure 1), and reveals a whole host of potential applications for the laser in clinical practice. Dr Tomalla presents a number of cases that he has encountered, each requiring different procedures, and he outlines the outcomes of those procedures having favoured the femtosecond laser over the traditional approach.

    We have been using the Femtec femtosecond laser at the Hospital for Refractive and Ophthalmosurgery in Duisburg, Germany since July 2004 and we can now look back on nearly two years of practical experience. We have not ceased to be fascinated by the broad diversity of possible applications for the device and we continue to see promising results in patients other than those receiving LASIK surgery. Yet, we believe that we have only scraped the surface of the possible uses of this exciting technology.

    How does it work?

    The femtosecond laser, which has both CE certification and FDA approval, is an infrared laser that works at a wavelength of 1,052 nm. It emits ultrashort laser pulses with a diameter of 0.001 mm at one-billionth of a second (10-15 sec). With the laser, tissue can be cut very precisely and with practically no heat development. The laser pulses develop their energy at a depth inside the cornea, which is exactly defined in advance. Each laser pulse creates a mini-gas bubble that separates the tissue (photodisruption). Three-dimensional, high-precision laser cuts can then be made within the cornea by means of thousands of computer-positioned laser pulses. In ophthalmosurgery, the laser is used primarily for cuts in the interior of the cornea, for example, for flap preparation prior to LASIK, or for preparation of corneal tunnels for intracorneal ring segment (ICRS) implantation.

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    Progressive keratoconus?

    Implantation of ICRS supported by femtosecond laser technology offers a new option in the treatment of progressive keratoconus with a clear central cornea because the laser can be used for exact preparation of the implantation tunnel. The advantages of the femtosecond laser over mechanical techniques are related to the intrastromal cuts, which can be made from inside to outside, the risk of infection is clearly reduced in every procedure, centric or eccentric fixation of the tunnel can be selected and the curvature of the cornea remains intact throughout the procedure. The patented patient interface ensures minimal flattening of the cornea to about 35 D.

    Figure 2: Preparation of implantation tunnel with newly-designed instruments.
    With the femtosecond laser, the cornea is prepared from inside at 70% depth. From there, a precise, previously defined tunnel 1 mm in width is created. Depending on the individual patient findings, the outer diameter is set between 8.0 mm and 8.8 mm and the inner diameter between 7.0 mm and 7.8 mm. The laser energy is 3.0 ÁJ and the spacing 8/10.

    Figure 3: Postsurgery: implanted intracorneal ring segments.
    Based on these very precise values, we can prepare a minimal implantation tunnel, which is adapted exactly to the ICRS and leaves no empty space. The intracorneal ring segments can then be easily implanted with new, specially designed instruments (Figures 2 & 3).


    Mark Tomalla, MD
    Mark Tomalla, MD works at the Clinic for Refractive and Ophthalmosurgery, Ev. u. Joh. Klinikum Niederrhein, Germany. He may be contacted ...

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