LaserSoft Dual – Combined UV Ablation Laser and Femtosecond Laser
LaserSoft Dual: Merging Refractive and Cataract SurgeriesThe Katana Solid State Laser Platform allows the proprietary and patented (US Patent no. 7,721,743 and 8,313,479) combination of UV-Ablation Laser and Femtosecond Laser in one single system, LaserSoft Dual (currently under development): surgical procedures include cornea ablation, laser microkeratome, corneal pockets, lamellar and penetrating keratoplasty, and cataract.
Advancing the State-of-the-Art in Ophthalmic SurgeryLaserSoft Dual combines Near Infra-red femtosecond laser system for femtosecond applications and UV nanosecond laser system for the corneal ablation. The benefit to the ophthalmologist is a more efficient system with lower maintenance cost with a highly stable and reproducible output, the benefit to the patient is an acceleration of the surgical procedure. From a technological point of view, this system overcomes the disadvantages of the excimer laser as well as the disadvantages of the femtosecond lasers on the market so far, by using the superior laser material Ti:sapphire.
State of the Art
The first step of a LASIK procedure (before applying the cornea-ablating UV-pulses) is a mechanical microkeratome cut into the cornea. This cut leaves an almost detached part of the cornea (the flap) which is folded back to allow ablation of the bulk part of the cornea. This action can cause different complications (event rate: 5%), mainly due to the risk of infections and inflammations. In recent years, pulsed femtosecond laser based procedures have been developed for flap cutting. Additional femtosecond laser based procedures include cataract surgery, to create corneal pockets, to perform lamellar and penetrating keratoplasty.
The femtosecond laser based non-invasive procedure of intrastromal vision correction reduces the risk due to infections but is limited to corrections up to few diopters.
The most frequently laser in refractive laser surgery is the ArF-Excimer laser. It shows several disadvantages like a beam quality that is difficult to reproduce and kept stable over a long time and the need for poisonous expendables (F2 gas). Additionally, due to the aggressive action of the 193 nm radiation onto optical surfaces high service and operation costs are caused by the excimer laser technique. The stronger absorption of the 193 nm radiation by water generates a certain unpredictability in the clinical results of excimer lasers and requires complex nomograms to achieve the desired correction.
The innovative features of the LaserSoft Dual are the following:
- The same solid state pumping laser is used for the generation of the UV-radiation and the fs-laser radiation.
- The fundamental pulses for the UV-pulse generation and the fs-laser pulses are generated with the same resonator/amplifier system.
- Cascaded second harmonic generation (ω + ω → 2ω; 2ω + 2ω → 4ω) is employed to generate UV-radiation in the wavelength range = 208 nm when the UV-part of the laser is in operation.
By a combination of a UV-laser, a femtosecond laser, 3-D tracking (or 2-D tracking with applanation), and a scanner system with appropriate scanning algorithms both is possible, the femtolaser related procedures as well as the ablation of the desired pattern for optimal vision correction.
The disadvantages of the excimer laser (poor beam profile, poisonous expendables) can be overcome by a cascaded frequency quadrupling (ω + ω → 2ω; 2ω + 2ω → 4ω) of a near infrared (NIR) solid state laser.
The laser material (Titanium-sapphire) used in the LaserSoft Dual has some advantages compared to the Nd: glass that is used in the femtosecond systems currently available in the market. These are:
- Higher pulse-to-background power ratio
- Smaller wavelength, leading to a more efficient (multi-photon-induced) evaporation
- Due to the higher bandwidth of Ti:sapphire, shorter pulses (in the order of 100 fs) are possible, which leads to a more efficient evaporation
- Compact design of LaserSoft Dual to generate femtosecond pulses and fundamental nanosecond pulses for generation of the UV-radiation.
Conventionally treated with the use of two different laser systems, combining femtolaser related applications and corneal ablations in one system – LaserSoft Dual - gives unique conveniences and advantages for the patients and the phisicians (e.g. compared to current technology, no transportation of the patient between two devices and/or no swivel of the delivery arm is needed), and cost efficiency.