March 2013

 

COVER FEATURE

 

Cataract/IOLs, femtosecond cataract

Update on the femtosecond laser for cataract surgery


by Michelle Dalton EyeWorld Contributing Writer

   
Key system for the femto

Table 1. Key system figures for the femtosecond lasers for cataract refractive surgery. Adapted and updated from Jonathan Talamo, M.D.

With more surgeons using the devices, quantifying the benefits may become easier

Femtosecond laser technology is a relatively new entity, first introduced for corneal surgery, then expanding its capabilities to include lamellar and penetrating keratoplasty, and now to capsulotomy and phacofragmentation in cataract surgery. Zoltan Z. Nagy, M.D., clinical professor of ophthalmology, Semmelweis University, Budapest, Hungary, believes that eventually most surgeons will be using a femtosecond laser in cataract surgerymuch like how most LASIK flaps are created with a femto today. Uncomplicated cataract surgery, where no other comorbidities exist, is already an incredibly safe surgery, "so it's hard to imagine being much safer," said William W. Culbertson, M.D., professor of ophthalmology, Bascom Palmer Eye Institute, Miami, but when surgeons start discussing the femto for cataract, "we're talking about having fewer complications and getting better outcomes in terms of vision while minimizing the damage to the cornea." Reducing the number of maneuvers a surgeon must do lessens the amount of phaco energy required to the point where "we're getting close to using no phaco energy at all," Dr. Culbertson said, citing published work from H. Burkhard Dick, M.D., and others.1

The technology is still in infancy, and while pricing, surgical time, necessary skills, and learning curves can all be debated, "the technology works, and a lot more development should be expected in this field in the near future," Prof. Nagy said.

Safer than manual procedures?

Femto update article summaryFemto for cataract "has the potential to increase the safety of cataract surgery because the precise corneal incisions, the perfect capsulotomy, and the lens fragmentation reduce the risk of an errant capsulorhexis, the amount ofphaco energy required to emulsify the lens, the amount of irrigation fluid running through the eye, intraocular manipulations, and the risk of a leaky wound," said Neil J. Friedman, M.D., adjunct clinical associate professor, Stanford University School of Medicine, and director of cataract and lens implant surgery, Pacific Vision Institute, San Francisco. (See the list of additional suggested references for more details.) No matter how good a surgeon someone is, "it's very difficult to make a perfect circle. It's very difficult to make the exact same size incision every single time," said Michael J. Endl, M.D., partner, Fichte Endl & Elmer Eyecare, Niagara Falls, N.Y.

Creating a corneal incision, capsulotomy, and fragmenting the crystalline lens can all be performed manually, "but with the aid of a femtolaser, we can have more central incisions, have exact size and diameters every time, and we can guarantee that the edge of the IOL will be covered by 0.25 to 0.5 mm anterior capsule to provide better centration compared to manual surgery," Prof. Nagy said.

For these experts, the ability of the femto to "improve the safety of surgery in challenging situations that have an increased risk of complications (i.e., mature cataract, dislocated lens, weak zonules, etc.)" is perhaps the most exciting, Dr. Friedman said. "Some data show that the refractive outcomes are slightly better due to a capsulotomy that perfectly overlaps the IOL optic keeping it closer to the predicted effective lens placement."

Prof. Nagy's group2,3 "achieved better centration, less posterior capsule opacification (our results will be published shortly), predictable geometry of corneal wounds, less endothelial stress and damage, and possibly less cystoid macular edema," he said.

The potential to improve safety "is incremental because any of the potential complications are still very rare," Dr. Friedman said. Tens of thousands of casesmaybe hundreds of thousandswill need to be performed with these technologies before a true claim of complication reduction can be made, he said.

Dr. Culbertson believes the femtolaser will inevitably lead to fewer cases of endophthalmitis "because the wounds don't leak," but also said more than 100,000 cases will need to be performed to show any true advantage. When the lens is broken up via laser instead of manually, "it's a little less likely to rip in the bag," Dr. Endl said, adding that, too, is a rare occurrence. Cases that used to be difficult with phacosuch as shallow anterior chambersare not as problematic "because the in-built optical coherence tomography controls the anatomy of the eye, and surgeons can avoid hitting the endothelial cell layer," Prof. Nagy explained. "In zonular dehiscence, femtolaser is a great advantage because we eliminate the zonular stress, and the SoftFit patient interface [Alcon, Fort Worth, Texas] can compensate for lens tilt."

Key attributes and drawbacks

A typical healthy LASIK patient can expect postop uncorrected vision of 20/20 upward of 95% of the time. Until recently, however, Dr. Endl said even the best cataract surgeons may achieve this outcome only 70% of the time. "The femto laser will look to make cataract surgery outcomes more precise and predictable," he said.

With acknowledged downsides of the technology being both the cost and the additional surgical time, the reproducibility "allows more surgeons and patients to ultimately benefit," Dr. Friedman said. "If cost/reimbursement issues and time were not an issue, femto would immediately become the preferred method of cataract surgery."

Prof. Nagy said there is a "promise for colleagues and patients that the benefits of the advanced technology IOLs can be better used if a femtolaser is incorporated into the ophthalmic practice." Dr. Endl said one difficulty with integrating the new technology is patient flow and trying to minimize the number of stops a patient has to make, but his patients have readily accepted the slight inconvenience.

Patient particulars

Not every patient is a candidate for the femtolaser, these experts warned. For instance, patients with small pupils (<6.5 mm) or significant corneal opacities are not ideal. Dr. Endl agreed, saying the technology has helped ease some of his fear in more difficult cases (the laser "doesn't care if it's a white cataractit'll put the circle anywhere you want it to go"), but none of the surgeons said the technology is without any potential complications.

Dr. Friedman said complications associated with the femtolaser are incomplete capsulotomy, a substantial increase in intraocular pressure during the procedure, or subconjunctival hemorrhage, "but that differs among the various devices." A partial capsulotomy "may account for anterior capsular tears," but surgeons should follow the contour of the capsulotomy during their learning curves to minimize the issue, Prof. Nagy said.

"Capsular blockage syndrome can also be avoided if the surgeon is using the so called 'rock-and-roll' technique: gentle hydrodissection and push down a bit and move the lens (rock and roll), then the gas bubble is allowed to leave toward the anterior chamber, not causing blockage syndrome," Prof. Nagy said. Avoiding the conjunctival vessels during wound creation will avoid the potential for an incomplete corneal cut, he said.

Ideally, Prof. Nagy said, he'd like to see a femtolaser "with multifunctional use: cataract, corneal surgery, possibly glaucoma control, and maybe vitreoretinal use. I do not know whether it can come true, we will see it. But without a vision, no development is possible."

Perhaps Juan Battle, M.D., said it best during last year's ESCRS conference: "The femtosecond laser in cataract surgery makes normal cases easier, tough or difficult cases like normal cases, and impossible cases possible," Dr. Culbertson said.

Mobile femto services

In the U.S., SightPath Medical (Minneapolis) is the first company to mobilize the femtolaser, and the company says as few as six cases a month will create profit for a center. Dr. Friedman said "it's a great service because it's going to allow more surgeons and more patients to benefit from the technology," and Dr. Culbertson said SightPath had similar success with a mobile excimer laser (Alcon's platform), so there is potential for surgeons who are interested in the technology but do not find it feasible to purchase on their own.

References

1. Conrad-Hengerer I, Hengerer FH, Schultz T, Dick HB. Effect of femtosecond laser fragmentation of the nucleus with different softening grid sizes on effective phaco time in cataract surgery. J Cataract Refract Surg. 2012;38:1888-1894.

2. Nagy ZZ, Kranitz K, Takacs AI, Mihaltz K, Kovacs I, Knorz MC. Comparison of intraocular lens decentration parameters after femtosecond and manual capsulotomies. J Refract Surg. 2011;27:564-569.

3. Kranitz K, Takacs A, Mihalta K, Kovacs I, Knorz MC, Nagy ZZ. Femtosecond laser capsulotomy and manual continuous curvilinear capsulorhexis parameters and their effects on intraocular lens centration. J Refract Surg. 2011;27:558-563.

Additional suggested reading

1. Friedman NJ, Palanker DV, Schuele G, et al. Femtosecond laser capsulotomy. J Cataract Refract Surg. 2011; 37:1189-1198.

2. He L, Sheehy K, Culbertson W. Femtosecond laser-assisted cataract surgery. Curr Opin Ophthalmol. 2011;22:4352.

3. Palanker DV, Blumenkranz MS, Andersen D, et al. Femtosecond laser-assisted cataract surgery with integrated optical coherence tomography. Sci Transl Med.2010;2:58ra85.

Editors' note: Dr. Culbertson has financial interests with OptiMedica (Sunnyvale, Calif.). Dr. Endl has financial interests with Alcon, Bausch + Lomb (Rochester, N.Y.), Merck (Whitehouse Station, N.J.), and Refocus Group (Dallas). Dr. Friedman has financial interests with OptiMedica. Dr. Nagy has financial interests with Alcon.

Contact information

Culbertson: w.culbertson@miami.edu
Endl: mpderme@aol.com
Friedman: njfmd@ymail.com
Nagy: nagy.zoltan_zsolt@med.semmelweis-univ.hu

Related articles:

Femto PK: A change in the corneal transplant paradigm by Martin L. Fox, MD, FACS

Femtosecond phaco techniques and outcomes by Vanessa Caceres EyeWorld Contributing Writer

Will femto cataract surgery stand the test of time? by Kerry D. Solomon, MD, refractive editor

How to perform femtosecond laser surgery for small pupil cases by William B. Trattler, MD

Femtosecond lasers for cataract surgery gaining ground, survey shows by Michelle Dalton EyeWorld Contributing Writer

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