Femtosecond Laser-assisted Cataract Surgery

Still in its early stages, this major advance raises promise of more precise, reproducible outcomes.

By John A. Vukich, MD

Cataract removal is an excellent procedure, proven on millions of patients over the course of decades and made dramatically better with the advent of foldable IOL implants and limbal relaxing incisions. Advances in IOL design may some day make it possible to reliably restore natural vision, achieving both emmetropia and smooth accommodation from distance to near. But the quality of our outcomes is still limited to our accuracy with manual incisions as well as our consistency in predicting effective lens position based on capsulotomy variability.

Soon, femtosecond lasers will be widely available to help us perform highly reproducible, precision-guided assistance in the removal of cataracts. This represents the first major advance in cataract surgery since phacoemulsification. The laser will enable us to bring standardization and reproducibility to corneal incisions and capsulotomies that have been done by hand, which have always had some variation from patient to patient.

The femtosecond laser fits intuitively with the advances that we've already made in cataract surgery. We've consistently developed less invasive and traumatic techniques, increased precision and predictability, eased recovery and produced better visual outcomes. The femtosecond laser complements and facilitates all of these goals. It delivers precise incisions, consistently sized and place capsulotomies, softens the lens for removal and helps treat astigmatism with accurate limbal relaxing incisions (LRIs). Together, these incremental improvements in current procedures represent a major advance.

Precise Incisions

Single-plane blades create a precise, reproducible corneal incision in terms of width, but it's not uncommon for the incision length to be slightly longer or shorter than intended. That extension or irregularity has become familiar to us, and we know how to work with it. However, we always aim to make incisions of a precise chord length within the cornea. That precision would remove the possibility of making an incision that leaks, as well as the possibility of iris prolapse if the incision is too peripheral. Patients would experience better healing as well.

With the femtosecond laser, we can place the incision anywhere we wish. We can use handheld instruments to do this, but the laser can precisely place the incision at the axis that the surgeon desires, offering another element of control and precision, as well as astigmatic control.

Consistent Capsulotomies

If we can precisely control the capsulotomy, we can more accurately control the positioning of the IOL and stabilize vision. The femtosecond laser gives us the capability to produce a consistently sized and placed capsulotomy (Figure 1). We can insert a bent needle into the lens and create a freehand tear in the capsule, but using a laser to make an incision with a precise location, size, depth and consistency is indisputably better. The use of a femtosecond laser all but eliminates capsular tags and inadvertent extension into the zonules, and provides consistent centration as well as size of the capsular opening. The effective lens power, which is dependent on where the implants sit within the capsular bag, is one of the least controlled aspects of conventional cataract surgery.

Figure 1. Laser cataract systems offer significant precision advantages in capsulotomy size, shape and centration.

Gentler Lens Removal

We know the amount of energy used for phacoemulsification correlates to endothelial cell loss as well as postoperative inflammation. Therefore, if we can limit the energy exerted on the eye, we can speed recovery and achieve better visual outcomes.

Femtosecond lasers have the ability to pretreat, segment or soften the lens to minimize the energy and trauma required for phacoemulsification and removal (Figure 2). This is compelling in terms of its potential to result in quieter eyes and better postoperative recovery, but with limited numbers of lasers in use, large-scale clinical trials are still needed to prove this hypothesis. However, it makes sense to believe that if we use the femtosecond laser to presegment the cataract and use less power than we would with phacoemulsification, then we may reduce the associated risks of the surgery. It seems likely that we will remove the cataract with less intraocular manipulation and minimize the undesirable outcomes associated with phacoemulsification.

Figure 2. Lens Fragmentation

Astigmatism Correction

When we treat astigmatism by placing LRIs, cataract surgery becomes a combined refractive procedure to restore vision. The femtosecond laser allows us to draw a precise arc and place the relaxing incisions at a uniform location relative to the pupil or limbus, with a uniform length and depth. The accuracy of using a handheld blade for refractive incisions is notoriously variable. A consistent incision isn't easy to obtain using a blade, and it directly relates to the reproducibility of the astigmatic effect. We've migrated many surgical incisions from manual to laser, and it makes sense to view this advance as another improvement in precision that will enhance visual outcomes.

A Transition for Surgeons

My experience using a femtosecond laser came as a consultant for OptiMedica, when as part of my involvement in their device's development, I used the laser in cataract surgery performed offshore. I immediately recognized that this was an exciting innovation—one that adds a level of excitement to the cataract procedure.

We all want things to be functionally smooth and operationally elegant, and the femtosecond laser certainly fulfills those ideals. I was able to get the capsulotomy exactly how I wanted it and was impressed by the effect of breaking up the nucleus to facilitate removal. It was clear to me that this is a major advance.

Practically, the laser itself introduces a new step into the cataract procedure. There is a learning curve as the surgeon is trained in the skills of executing the instrument settings and using the device, but anyone who uses a YAG laser for capsulotomy can quickly understand and use a femtosecond laser.

In terms of time management, the device is designed to facilitate patient flow in the operating room. In surgery centers where multiple surgeons are operating simultaneously, the laser is designed so it can be stored outside of the operating suite and used by several doctors. In those situations where a single surgeon will use the laser, it can be located in the operating room. The actual time to perform the femtosecond laser treatment is only a minute or two and the efficiency subsequently realized at the time of lens removal of the preconditioned cataract more than makes up for that lost time.

How Close Are We?

Two femtosecond lasers are currently approved in the United States for cataract treatment. The LenSx (Alcon) and LensAR lasers (LensAR, Inc.), have received FDA clearance for use in the United States, however there are currently only a handful of these units in operation. Two other manufacturers (OptiMedica Corporation and Technolas Perfect Vision) are rapidly moving through the approval process for new devices—a race that points to strong market potential for these lasers. Adoption of the femtosecond laser approach hinges on clinical and practical acceptance.

In my experience talking to colleagues, the vast majority of surgeons already believe in this technology philosophically. They believe that a femtosecond laser can do what studies say it does, which means that most surgeons accept that the femtosecond laser may be a valuable tool for improving cataract surgery. Most surgeons say they would use it if they could make sense of it financially.

When I ask surgeons if they would use a femtosecond laser if it were free, virtually everyone says “yes,” but new technology comes at a cost. So we need to determine how the costs will be borne and reconcile this with the benefits of using femtosecond lasers. This is a premium procedure, so should we recognize it as such and increase the charge to the patient, so it is tied to the overall premium costs that are associated with implantation of premium IOLs? The answer is not yet clear, and we will need more information and input from insurers and Medicare.

Putting it all together

History Repeating

Eventually, the clinical and practical factors will iron themselves out. As more lasers enter the market, the procedure will affect IOL design, financial issues will be resolved, the benefits to patients will become clearer, and femtosecond lasers will become more of a necessity for surgeons. Certainly, it's hard to imagine that at some point in the future, we won't look back at freehand capsulotomy as part of the interesting history of ocular surgery in the same way we look at microkeratomes for creation of the LASIK flap.

Overall, I think the adoption rates for femtosecond lasers will follow a pattern similar to the introduction of phacoemulsification in the 1970s. Back then, many surgeons were happy with large incisions. They thought that maybe phacoemulsification was an unnecessary technology, but most thought it was interesting, so they took a wait-and-see approach. Fast-forward 40 years and this technology is used in the overwhelming majority of cataract surgeries performed in developed nations. Likewise, the adjunctive development of foldable implants, facilitated by the small incision, added another clinical advantage and became standard. The tipping point is when 30% of practices adopt a new form of technology. That's when everyone else gets on board or risks getting left behind.

It's the excitement of a new major advance in cataract surgery that puts me in that initial 30%. I look forward to finding out just how much more precise, reproducible and consistent our results can be if we migrate from manual surgical procedures to the femtosecond laser.

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John A. Vukich, MD, is surgical director at the Davis Duehr Dean Center for Refractive Surgery in Madison, Wisc., and assistant clinical professor of ophthalmology at the University of Wisconsin, Madison.