Experience with femtosecond corneal surgery guides surgeons through cataract transition

As much of the news concerning femtosecond lasers focuses on cataract surgery, today more than half of LASIK procedures are performed with femtosecond lasers to create the flap. While the machines differ in their function, this wealth of experience using femtosecond lasers in one application in the eye should be a tremendous resource for surgeons so they know what kind of performance and challenges to expect when moving into performing cataract surgery with the new laser platforms.

Since the introduction of the technology in the United States in 1999, refractive surgeons have been accumulating experience as the technology improves. With experience brings insight, and the experienced surgeons have gained insights regarding advantages and challenges of the lasers.

For the corneal refractive surgeon, the laser platforms have gone through generational changes and improvements such that corneal surface procedures are deemed by most as safe and effective. For the cataract surgeon, experience with laser technology is not as extensive, but advancements are being made.

Sonia H. Yoo, MD, noted the complications of early femtosecond laser platforms for corneal surgery include transient light sensitivity, an opaque bubble layer, epithelial breakthrough and anterior chamber bubbles. Image: Craig Denis Photography

“It is a very exciting technology that has changed the way refractive surgery and now cataract surgery are being performed,” Sonia H. Yoo, MD, said.

Dr. Yoo believes that femtosecond lasers have changed the field of refractive correction by making LASIK more safe and effective. Today’s femtosecond laser serves as a more refined cutting tool than the blade of a microkeratome by allowing for customizable LASIK flaps regarding depth, diameter, hinge angle, hinge position and side-cut angle, she said. This in turn has improved visual outcomes and the overall safety of the procedure.

A look at the lasers

In a presentation at OSN New York 2011, Dr. Yoo reviewed the five femtosecond laser systems for corneal refractive surgery that are available in the U.S.: IntraLase (Abbott Medical Optics), Femtec (Technolas Perfect Vision), VisuMax (Carl Zeiss Meditec), Femto LDV (Ziemer) and WaveLight FS200 (Alcon).

“All of these lasers work in the near-infrared region, have very small spot sizes and high repetition rates,” Dr. Yoo said. “What’s different about these platforms is that the speed of the lamellar cut goes anywhere from pretty fast to über fast.”

Dr. Yoo’s practical experience is with the IntraLase, VisuMax and WaveLight.

“We can actually see what we’re going to cut, what we plan to cut, before we make the cut,” she said.

The Femto LDV differs most from the other lasers in that it is more portable and has lower pulse energy and spacing and higher pulse frequency, according to Ronald R. Krueger, MD, MSE.

Ronald R. Krueger

“The effect of flap creation is different in that the separation is more influenced by the overlapping ablation of tissue, while the other systems have non-overlapping spacing with expanding cavitation bubbles that help to cleave the tissue apart,” he said. “The flaps also do not have a separate angled side cut, but rather taper to the periphery as with a microkeratome.”

Complications

Comparing complications associated with use of a mechanical microkeratome vs. a femtosecond laser, Dr. Yoo said that femtosecond laser complications are fewer, less severe and more easily treatable.

The more common complications include transient light sensitivity, the presence of an opaque bubble layer, epithelial breakthrough and anterior chamber bubbles within the tissue.

The original inflammatory complications and side effects of transient light sensitivity, diffuse lamellar keratitis and focal interface haze have been minimized, according to Dr. Krueger, and problems with bubbles have also been reduced.

“Opaque bubble layer still occurs with the higher-pulse energy lasers, but each [system] has ways to minimize its formation,” he said. “When bubbles escape through the trabecular meshwork, anterior chamber bubbles may form, and these can interfere with the tracking system of the excimer laser during refractive ablation. With the need for dissection of thin flaps after laser pulsing, flap tears can be experienced when careless in dissection, and bubble breakthrough can occur when unrecognized scars with a plug of epithelium reaches down to the layer of laser pulsing.”

While these complications have been experienced, he said, they are infrequent and rarely seen with newer systems.

Dr. Krueger said that the opaque bubble layer can be reduced by proper spacing and pulsing energy, and by avoiding a hard dock with the laser. It is also helpful to avoid extension of the canal to the limbal vasculature or the edge of the meniscus.

Ramon Naranjo-Tackman, MD, has also experienced the common complications of femtosecond laser use in his practice: “I have seen transient light sensitivity, opaque bubble layer, epithelial breakthrough and anterior chamber bubbles. I must insist, though, that after a while, the machines became almost free of complications.”

He has also experienced loss of suction and decentering of the procedure; however, Dr. Naranjo-Tackman believes that it is important to consider that none of the complications are irreversible.

His approach to mitigating problems, though, is to learn from experience. Staying educated and moving forward with technologies are the most essential steps in avoiding complications, he said.

“Learning and practicing in wet labs, reading the peer-reviewed articles and all the possible information in the field, attending meetings, asking physicians with experience, and overall accepting that certain technologies despite their costs are here to stay and really have advantages over less expensive technologies” Dr. Naranjo-Tackman said. “Physicians have to make efforts to get the technology, learn it and be skilled with it.”

As well, proper patient selection can help surgeons avoid potential problems and improve safety and visual outcomes.

Dr. Naranjo-Tackman recommended that ophthalmologists spend more time with the patient and explain that while the procedure has been shown to be safe, it does require patient cooperation.

Dr. Yoo agreed, noting that in systems with low vacuum, for example, patients must be fully cooperative so they do not break the vacuum, although losing suction is uncommon.

Surgeons must be aware of all details that are involved in their cases, according to Zoltan Z. Nagy, MD.

Zoltan Z. Nagy

“The surgeon must know all details of the cornea, the refractive error and the small anatomical details of the patient’s eye. One has to detect the earliest signs of forme fruste keratoconus to avoid postoperative complications,” Dr. Nagy said. “But first of all, the surgeon must communicate with the patient.”

Future of femtosecond technology

While good results have been seen by cornea and refractive surgeons, Drs. Naranjo-Tackman, Yoo and Krueger all look to the arena of cataract surgery as the future focus of femtosecond technology in ophthalmology. There is also potential with all-in-one platforms.

“The future is, of course, cataract surgery by femtosecond laser,” Dr. Naranjo-Tackman said.

“Perhaps one laser can do everything,” Dr. Yoo said. “There are femtosecond lasers available for cataract surgery and lens softening. As this technology develops, we might see femtosecond lasers that have more popular applications or have one laser that can do more things, rather than having separate ones for all applications.”

Dr. Krueger sees the future in expanded uses as well: “Femtosecond lasers have revolutionized refractive surgery, with greater than 50% of all U.S. LASIK surgeries using femtosecond laser. They have also offered great advantage in corneal surgery and are now gaining great attention in nucleus fragmentation, laser capsulotomies and laser-created corneal incisions for cataract surgery. I believe their influence will continue to grow into other areas of ophthalmology, such as glaucoma, strabismus and vitreoretinal.”

Femtosecond cataract systems

Even though femtosecond cataract technology is a developing and expensive technology, Dr. Yoo said that she believes the surgical results will drive how ophthalmologists use these platforms in their practices.

“If we see the results with its use are better in the field of cataract surgery specifically, we will likely see a shift in how to pay for it like we did in the field of refractive surgery,” Dr. Yoo said

The three systems that are approved in the United States for cataract indications, including anterior capsulotomy and phacofragmentation, are LenSx (Alcon), LensAR Laser System (LensAR) and Catalys Precision Laser System (OptiMedica).

Uday Devgan, MD, Healio.com/Ophthalmology Section Editor, said femtosecond technology has already begun to change cataract surgery, in that the lasers are able to make an incision with a particular type of architecture that is not possible with a manual blade. The technology allows for the creation of astigmatic relaxing incisions that can be titrated even in the postoperative period and for a high degree of accuracy and precision in creating a capsulorrhexis.

“While this is seemingly not such a big deal now, wait until we have specialized IOLs that require a certain size or shape of capsulorrhexis that can’t be created by hand,” Dr. Devgan said.

The lasers also allow for chopping of the nucleus before entering the eye, which in turn helps minimize the ultrasound phaco energy that is needed to divide the nucleus.

“We are using the very first generation of these femtosecond lasers, and like all technologies, they will evolve with time. The cataract surgery that I will be performing 5 or 10 years from now will also evolve into an entirely different procedure that produces better outcomes for our patients,” Dr. Devgan said.

Dr. Nagy is credited with performing the first cataract procedure with a femtosecond laser in August 2008 at Semmelweis University, Budapest, Hungary. His experience to date with femtosecond technology has been favorable, he said.

“Femtolaser in cataract surgery offers more predictable results and more consistent results for surgeons and for patients,” Dr. Nagy said. “The surgeon can achieve a guaranteed size and centered capsulorrhexis. With a perfect capsulorrhexis, we can have all the advantages of the premium lenses and we can provide better visual quality for our patients.”

Challenges

With femtosecond laser-assisted cataract surgery there can be air bubbles in the anterior chamber, smaller bubbles around the capsulorrhexis edge and larger gas pockets in and around the lens nucleus, Dr. Devgan said.

“Creation of intraocular gas bubbles can pose some challenges, but they can also be used to help with the procedure, such as with pneumo-dissection of the cataract from the posterior lens capsule,” he said.

Another disadvantage is that femtosecond laser procedures require patients to be fully cooperative so they do not break vacuum.

In addition, laser angle is key when performing this procedure, he said. If the laser is misaligned by even a fraction of a millimeter, the energy delivery can be misdirected with unexpected results, such as a partially completed capsulorrhexis.

“Even with a perfectly cut capsulorrhexis, there can be additional surgical challenges,” Dr. Devgan said.

When the laser cuts the capsulorrhexis, it also neatly cuts the anterior cortical layer of the cataract. Strands of anterior cortex are typically grabbed in order to completely clean the capsular bag during irrigation and aspiration, and if these strands are no longer present, alternate techniques must be applied, Dr. Devgan said.

Minimizing drawbacks

Surgeons may be able to mitigate these issues by adapting their techniques to newer platforms, Dr. Devgan said.

“So far my experience has been good, but I am conservative in my approach,” he said. “Like any new technology, there is a new and unique learning curve and a new potential set of complications. And remember for certain challenging cataract cases, such as patients with small pupils or truly opaque cataracts, you may not be able to deliver the laser energy to the target tissue and you’ll have to revert to your traditional manual technique.”

Dr. Nagy said complications resulting from femtosecond laser use exist, but with proper energy level and spot separation, these dangers can be minimized.

“With the femtolaser for cataract surgery, I had no side effects that would have affected the final visual outcome,” he said. “I was also very cautious. With practice, the complication also decreases.”

“Femtosecond lasers changed the field of ophthalmology. There are tremendous new possibilities with this new technology, and I am sure we will see things we would not even think of until they became available for ophthalmologists,” Dr. Nagy said. “This is the future, and I expect to eventually see combined lasers that could do many procedures at the same time — corneal, lenticular, maybe retinal. Ophthalmology always had a pioneer role in laser technology and kept this advantage during the past 50 years of laser technology within medicine.” – by Tara Grassia

References:

Ecsedy M, Miháltz K, Kovács I, Takács A, Filkorn T, Nagy ZZ. Effect of femtosecond laser cataract surgery on the macula. J Refract Surg. 2011;27(10):717-722.

Masket S, Sarayba M, Ignacio T, Fram N. Femtosecond laser-assisted cataract incisions: architectural stability and reproducibility. J Cataract Refract Surg. 2010;36(6):1048-1049.

Medeiros FW, Stapleton WM, Hammel J, Krueger RR, Netto MV, Wilson SE. Wavefront analysis comparison of LASIK outcomes with the femtosecond laser and mechanical microkeratomes. J Refract Surg. 2007;23(9):880-887.

Ravin JG. Controversy in ophthalmology at the beginning of the 20th century: opinions voiced in the archives, especially on cataract and glaucoma. Arch Ophthalmol. 2011;129(1):97-101.

For more information:

Uday Devgan, MD, can be reached at Devgan Eye Surgery, 11600 Wilshire Blvd., Suite 200, Los Angeles, CA 90025; email: devgan@gmail.com.

Ronald R. Krueger, MD, MSE, can be reached at Cole Eye Institute, Cleveland Clinic, 9500 Euclid Ave. i32, Cleveland, OH 44195; email: krueger@ccf.org.

Zoltan Z. Nagy, MD, can be reached at Semmelweis University, Maria u. 39, H-1085 Budapest, Hungary; email: zoltan.nagy100@gmail.com.

Ramon Naranjo-Tackman, MD, can be reached at National University of Mexico, Mérida #119, Colonia Roma 06700, Mexico DF; email: naranjo_cornea@yahoo.com.

Sonia H. Yoo, MD, can be reached at Bascom Palmer Eye Institute, 900 Northwest 17th St., Miami, FL 33136; email: syoo@med.miami.edu.

Disclosures: Dr. Devgan is a speaker or consultant to Alcon, Bausch + Lomb and Carl Zeiss Meditec. Dr. Krueger is a consultant for Alcon/WaveLight. Dr. Naranjo-Tackman is a consultant for LensAR. Dr. Nagy is a consultant to Alcon/LenSx. Dr. Yoo is a paid consultant for Alcon, Bausch + Lomb, Carl Zeiss Meditec and Transcend. She receives research grants from Allergan and Genentech.

Does the use of femtosecond laser-assisted cataract surgery benefit ophthalmologists?

Paradigm shift may occur

Johnny L. Gayton

Femtosecond laser-assisted cataract surgery provides the physician with several current benefits. The corneal incisions are symmetric and precise. I am confident that this increases the predictability of corneal arcuate incisions.

I have been using arcuate incisions made by hand with a diamond blade for more than 25 years. When the acrylic toric lens was released, arcuate incisions were relegated to an enhancement role in my practice, because the toric IOL was much more predictable and stable than manual arcuate incisions could accommodate. I think that was due in part to inconsistent depth and shape of manual incisions. With the introduction of the femtosecond laser, arcuate incisions have definitely moved back into my list of options for patients with astigmatism.

The femtosecond laser has also reduced the likelihood of corneal tunnels that are either too short or too long. The other main surgical benefits of femtosecond cataract surgery deal with the lens. The capsulorrhexis size is controlled to 0.1 mm and can be centered very precisely. This may make the effective lens position more predictable. I have manually performed tens of thousands of capsulorrhexes, yet I still have the occasional opening that is too small, too large or decentered. That problem has been virtually eliminated in femtosecond cases. The femtosecond treatment of the nucleus has not been as beneficial as the opening of the anterior capsule, but at times it is very helpful, such as in narrow angles, and it probably reduces the amount of ultrasonic energy required to remove the nucleus.

Another major benefit is that it further distinguishes our premium packages from traditional cataract surgery. Patients have a genuine comfort with the idea of having laser surgery. We have found that patients are much more likely to upgrade now that we are offering femtosecond cataract surgery.

Because the technology is so new, I think there will be other benefits realized as the field of femtosecond cataract surgery develops. We may very well be on the cusp of another paradigm shift in ophthalmology akin to the transitions from couching to intracapsular cataract extraction to extracapsular cataract extraction to phaco to microincision phaco and now femto-phaco.

Johnny L. Gayton, MD, is CEO of Eyesight Associates and an adjunct professor of ophthalmology at Mercer Medical School, Ga. Disclosure: Dr. Gayton is on the speakers bureau for Alcon and Ista.

Procedure still in the beginning stages

William I. Bond

At the current time, it seems to me that femtosecond laser-assisted cataract surgery is in its infancy. The technology may justify its hype in the long run, or it may not. Extravagant marketing claims are made for the technology (some seem even misleading, such as “no actual cutting”), but it remains to be seen whether it can deliver on these claims.

Troubling questions exist. One brief example: There has been much hand-wringing and angst over the years about the effects of the very brief suction pressure used during routine LASIK and the questions of whether this could induce retinal and vascular complications. The suction device used with the femtosecond laser for cataract surgery will be used for at least a comparable period of time as in LASIK and on what one must assume to be a much older population, with presumably more easily compromised retinal blood flow. This would seem to require some serious thought and study before being regarded as entirely safe.

Peer-reviewed journal articles with, one hopes, no commercial bias continue to be keenly awaited. What benefits patients benefits physicians, and one must keep an open mind. If the femtosecond results are indeed found to be superior in the long run with large numbers of eyes, the patients will have the boon of a superior method, and that would be a great thing.

The current economic model proposed for the femtosecond cataract laser system appears to me to be not at all beneficial to the physician. The physician is faced with a colossal up-front investment, a substantial click fee, a service contract and the all-but-inevitable high cost of future technology upgrades. He or she is further faced with fairly significant uncompensated extra time per surgical case. I have heard blithe statements at meetings that patients will want this presumed better technology and will happily pay for it, and I have no doubt that this may be true in the occasional case, but one finds it hard to think that this will be true in the general run of routine cases.

William I. Bond, MD, is medical director of Bond Eye Associates, Pekin, Ill. Disclosure: Dr. Bond is a paid consultant to Alcon.