Femtosecond lasers may become complex tools in ophthalmic surgery

The lasers are mostly used as flap-makers today, but an expert says they will become important for a variety of surgeries.

The success of LASIK as a surgical tool to correct refractive errors has been a driving force for technology. Even though in Europe almost 80% of the total flaps are still made with mechanical microkeratomes, it should be acknowledged that most of the patients and refractive surgeons would prefer a femtosecond laser microkeratome to a mechanical one in LASIK surgery.

Jorge L. Alió

The main arguments for this choice are increased safety and control; it is a more advanced surgical concept and is a more attractive option for patients. Patients prefer femtosecond LASIK, and the “magic” of laser is regarded as a safer and better surgical approach in the minds of most patients who demand refractive surgery. In this environment, refractive surgery provides more demand for femtosecond technology than any other surgical area.

We are now faced with the question: Are femtosecond lasers in ophthalmology going to be more than a simple way to create sophisticated LASIK flaps?

Femtosecond technology

There are four femtosecond laser technologies commercially available today. IntraLase (Advanced Medical Optics) is the only non-European laser; the Visulas (Carl Zeiss Meditec), the Femto LDV (Ziemer) and the Femtec (20/10 Perfect Vision) are European. These four femtosecond lasers are distinctive in their technology and approach the market with different offerings.

IntraLase, the most popular and globally disseminated laser, offers excellent performance in LASIK flap creation as its main achievement. Alternatively, it is offered for intracorneal tunnel creation, arcuate incision for the correction of astigmatism, penetrating graft and lamellar graft surgery, but there are limitations for these indications. Secondary indications are of marginal interest with this laser.

Femtec offers intrastromal ablation (the intraCOR procedure) as an innovative application and a novel technique for low myopia and presbyopia correction based on radial or concentrical applications of the femtosecond energy. It is also offered for the performance of corneal graft surgery without corneal applanation.

Femto LDV focuses mainly on flap creation. Recently, an application for creation of intracorneal ring segment tunnels was introduced.

Visulas approaches both LASIK and corneal grafting surgery without corneal applanation.

The capabilities of these technologies are important, as numerical aperture (directly related to the capability of focusing energy on a given plane, creating a finite area of expansion with a bubble), the way in which they manipulate the energy to be focused and their capability of working on curved surfaces make distinctive differences between them. Even though corneal surgery is an attractive option, most surgeons today do not consider this is a practical application of the technology. Most of these options, such as grafting surgery (either penetrating or lamellar), tunnel creation for intracorneal ring segments, arcuate incisions and other marginal options, are still considered speculative, as outcomes have been diverse and are useful only in a minority of patients.

It seems unrealistic to consider that corneal surgeons will buy a femtosecond laser only to create lamellar grafts for corneal grafting, as the profitability of this surgery would be unbalanced. Instead, it is conceivable that corneal tissue will be manufactured at corneal banks using femtosecond machines to offer the surgeon either superficial or endothelial lamellar grafts in good conditions. It should be acknowledged that most of the corneal applications are going to remain as a marginal needs indication of femtosecond lasers.

Future possibilities

Femtosecond lasers are a powerful and flexible surgical tool. They can be used in scleral surgery and in vitreoretinal surgery, and scientific evidence shows that they may be useful to change the index of refraction of ocular tissues such as the cornea and lens in precalculated ways, creating a new ophthalmic surgery concept. In connection with nanobiomaterials, new femtosecond surgical tools will be created, opening the path for nanosurgical technology, something that seems to be a dream today but will certainly be possible. Glaucoma, vitreoretinal and most innovative forms of refractive surgery will appear on the horizon as future developments of this technology. The surgical application of femtosecond lasers could be huge in the future.

Despite the limited applications possible today, femtosecond technology is not going to be just a flap-maker technology, but rather one of the most important, challenging and exciting areas of clinical and technological research in ophthalmic surgery in the coming years.

Jorge L. Alió, MD, PhD, can be reached at Vissum, Instituto Oftalmologico de Alicante, Avda. de Denia, s/n, 03016 Alicante, Spain; +34-965-150-025; fax: +34-965-151-501; e-mail: jlalio@vissum.com.