The Ultrastable and Compact Femto LDV

The Femto Leonardo Da Vinci (Femto LDV; Ziemer Ophthalmic Systems AG, Port, Switzerland)—formerly known as the Da Vinci—is the first femtosecond laser to offer a movable flap creation workstation. Modeled after a handheld mechanical microkeratome, the Femto LDV is small enough be installed next to the excimer laser, so that the patient may stay on the same patient bed throughout both flap creation and ablation. This allows for an integrated procedure, facilitating speedier procedure times and workflows within a refractive practice.

What sets the Femto LDV apart from other femtosecond lasers is its technical and operational concepts. Operationally, the Femto LDV laser is not only small and ultrastable, but its compact size allows for easy transportation within the operating room and even between multiple locations. It is appropriate for those surgeons who work as a mobile laser service, because bulkier laser models are more sensitive to environmental changes. With a larger femtosecond laser, it is harder to alter location, even within the same operating room.

Perhaps the bulkiest component of any femtosecond laser system is the amplification stage, which consumes a lot of energy, generates excess heat, and causes the equipment to be sensitive to environmental conditions. The Femto LDV does not require a separate amplification stage, and therefore, its energy output is substantially reduced. This is important aspect of the laser, because it offers added safety.

The Femto LDV operates at a very high laser pulse rate of several MHz, approximately 1,000 times faster than other conventional femtosecond lasers. This results in very short laser pulses (200 femtoseconds to 300 femtoseconds) of low energy density, reducing the potential for undesirable side effects (eg, tissue coagulation, cavitation bubbles leading to opaque bubble layers in the stromal tissue).

When you look at the size of each individual spot, you will see that they are small and tightly spaced—to the point that the spots actually overlap. With this small spot size, complete tissue dissection occurs in the plane where you want to cut the tissue, leaving no tissue bridges. While actual cutting times are comparable with conventional femtolasers, total procedure times (ie, total time of contact between laser and cornea) and most importantly, suction times (ie, time from suction-on to suction-off), are much shorter (approximately 45 seconds).

The Femto LDV was Conformitée-Européenne (CE)-approved and cleared by the US Food and Drug Administration (FDA) in October 2005. Currently, shipments are being made to centers across Europe, and more than 1 dozen European centers have experience with this laser. Approximately 400 flap creations have been performed with the Femto LDV. While clinical experience with the Femto LDV is still limited, results thus far have been promising. The first clinical data will be presented at the Association for Research in Vision and Ophthalmology (ARVO) and the American Society of Cataract and Refractive Surgery (ASCRS) annual meetings in April and May, respectively.

According to user feedback, there is a minimal learning curve, and surgeons are excited with the cut quality as well as the nice stromal bed created by the laser, both of which enhance postoperative visual recovery. The final result depends largely on what is done with the excimer laser and not just on the quality of the flap, however, several upcoming trials are studying visual quality with the Femto LDV versus mechanical microkeratome. At 1 day after and 1 week after surgery, visual results were better with the Femto LDV. At 1 month, however, visual results were comparable between the devices. It was concluded that, due to a more favorable flap quality with the Femto LDV, recovery were faster with the femtosecond laser. These first few trials are good indicators as to what these future papers will have to say about this product.

The Femto LDV is still at its beginning stages of clinical experience. With time, surgeons who use this system will be able to delve into other corneal surgery applications. Currently, Ziemer Ophthalmic Systems AG is developing a secondary energy delivery system that will be compatible with various corneal surgery procedures including corneal transplantation and creating tunnel incisions for intrastromal rings. This capability is expected to be available later this year. Some other femtosecond laser models have already demonstrated the capability to perform these procedures, however, only a small ratio—in the parts per million—of secondary procedures are being done versus flap creation for LASIK. As a whole, this industry is at the very early stages of creating a versatile machine for corneal surgery. LASIK will—for quite some time to come—represent the bulk of applications for any femtosecond machine.

Anton C. Wirthlin, PhD, is Vice President, Marketing & Communications at Ziemer Ophthalmic Systems AG (a Ziemer Group Company). Dr. Wirthlin states that he is salaried by and owner or shareholder in Ziemer Group AG. He may be reached at +41 32 332 7052; anton.wirthlin@ziemergroup.com.