THE FUTURE OF CATARACT SURGERY

POINT by Kendall E. Donaldson, MD, MS

The debate over laser cataract surgery began at least 10 years before FDA approval of femtosecond lasers in cataract surgery. Since its approval four years ago, surgeons have become even more passionate in support of or in opposition to its use. Although traditional phacoemulsification delivers reasonable safety and refractive outcomes, femtosecond laser-assisted cataract surgery (FLACS) has the potential to allow cataract surgery to evolve to even a higher standard, creating exceptional, more predictable outcomes. Particularly when FLACS is teamed up with other technology such as intraoperative aberrometry and surgical planning systems (such as Alcon’s Verion or Zeiss’ Callisto), our refractive outcomes can be fine-tuned to the highest levels of precision.

Patient undergoing treatment with the Alcon LenSx femtosecond laser.
COURTESY KENDALL E. DONALDSON, MD, MS

Another progressive step

Cataract surgery is constantly in evolution. Since the introduction of FLACS just four years ago, the improvements in both software and hardware have been impressive. These upgrades allow us to provide patients with much greater efficiency (my prior treatments of 90 seconds are now down to 20 to 30 seconds on average), increased precision and improved imaging capabilities with high resolution. We have also benefited from user interface improvements (it’s more intuitive, with increased ease of use for the technician and the surgeon) and patient interface modifications (the smaller diameter offers increased patient comfort and easier docking).

FLACS has become a refractive procedure poised to compete with LASIK with regard to visual outcomes. Femtosecond lasers, along with intraoperative aberrometry and integrated cataract suites, provide the framework that will help us take our patients to the next level of superior refractive outcomes and the highest levels of patient safety.

Practice makes perfect

When considering the resistance to this transition, we need to reflect on previous advancements in cataract surgery, including the evolution from extracapsular cataract surgery to phacoemulsification and the trend from post-op aphakia to standard use of IOLs. When Charles Kelman introduced phacoemulsification in 1968, it was met with great opposition from those comfortable performing extracapsular cataract surgery. A similar antagonistic response ensued during the transition from aphakia to the standard usage of IOLs around that same time, as many saw those early adapters as rebellious miscreants.¹ With time, these advancements became the standard of care, and they continue to evolve.

The learning curve for FLACS is similar to or faster than the learning curve associated with traditional phacoemulsification. The transition to femto requires fewer than 100 FLACS cases, after which surgeons may potentially experience fewer complications compared to traditional phacoemulsification.² Also, recent evidence supports that FLACS is equally safe or safer than traditional phaco, particularly among residents in training with minimal to no experience in the operating room.^3-5

Precise cuts

Femtosecond lasers can create a centered capsulotomy of a specific shape and size. Although we may pride ourselves in our ability to create a “perfect” rhexis, in my opinion it is virtually impossible for a surgeon to compete with the laser’s accuracy down to the micron with regard to size and centration, and to achieve that degree of perfection in every case.

This degree of precision may be more crucial with accommodating lens technology. With several IOLs in the pipeline, such as dual optic accommodating designs, centration and accurate effective lens position will be essential. Regarding regularity of the capsulotomy edge, this has fortunately not translated into any actual weakness in the capsule that could lead to an increase in complications.^6,7 One study showed that a laser-created capsulotomy is stronger than one created manually.⁵

Treatment plan for the AMO Catalys femtosecond laser.
COURTESY KENDALL E. DONALDSON, MD, MS

Treatment plan for the AMO Catalys femtosecond laser.
COURTESY KENDALL E. DONALDSON, MD, MS

Using femtosecond lasers to create precise arcuate incisions allows us to customize astigmatism correction to achieve high levels of precision. To further optimize astigmatism correction, nomograms, which are still under development, will be used in conjunction with integrated cataract suites and outcome analysis measures to improve our ability to achieve outcomes closest to emmetropia.

Complicated cases

I prefer using the femtosecond laser for my more complicated cases. By prefragmenting the mature lens, I can confidently remove the nucleus with a much lower energy expenditure causing less trauma to the eye, potentially resulting in less endothelial cell loss.^8,9 Also, in a patient with pseudoexfoliation or a traumatic cataract (with potential zonular dehiscence), lens prefragmentation allows me to remove the lens with less zonular stress. Numerous studies have shown that the femtosecond laser helps reduce energy dissipated into the eye during phacoemulsification on all available laser platforms.^8,9 This may translate into gentler surgery in patients with vulnerable eyes, such as those with Fuchs’ Dystrophy.¹⁰ However, even in patients with normal eyes, less traumatic surgery may result in faster healing and better visual outcomes. Recent studies have shown promising results with regard to visual outcomes after FLACS compared with traditional phacoemulsification; however, further larger, prospective studies are ongoing.^12,13

Justifying the cost

Increased cost and decreased efficiency are often inherent to adding any new technology that offers a higher level of patient care, including the latest surgical microscopes, phacoemulsification platforms and video recording technologies. We are providing patients with an additional service by correcting their astigmatism and possibly inserting a premium IOL, with the expectations that they will achieve a better visual outcome.

All new technology comes with a price, so surgeons must weigh the financial commitment, anticipated gain and clinical impact to determine whether this is the best choice for the practice. FLACS will continue to evolve, and some surgeons may choose to wait until it becomes more mainstream and more affordable. However, I’ve seen the conversion rate steadily increase among my colleagues.

Conclusion

We are witnessing the early stages of a transition toward increasing precision in cataract surgery. Femtosecond laser technology will continue to advance.

It has the ability to make our surgery more precise and predictable, which may translate into increased precision with outcomes and increased safety through reductions in energy. OM

Kendall E. Donaldson, MD, MS, is associate professor at the Bascom Palmer Eye Institute, where she specializes in cornea/external disease and cataract/refractive surgery. She is medical director of the Bascom Palmer Eye Institute in Plantation, Fla. Disclosure: Dr. Donaldson is a consultant for Alcon and AMO.

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A STEP IN THE WRONG DIRECTION

COUNTERPOINT by Steve Safran, MD

Whenever surgeons consider making a change in their surgical technique, I believe they should be motivated by the desire to achieve certain objectives. Such change ideally should reduce surgical time, the procedure’s cost, complexity and complication rates while improving overall quality of outcomes.

Here, I present some of the evidence that shows why using a femtosecond laser for cataract surgery is a step away from accomplishing these objectives.

Capsulorhexis and rhexis results

The femtosecond laser was introduced for cataract surgery in 2010 with the promise that a perfect, round, cookie-cutter, laser-created uniform capsulorhexis in every case would improve refractive outcomes. Despite no clinical evidence to support such a notion, the claim was an early selling point for the technology. A 2013 study, however, demonstrated that capsulorhexis size and shape have no significant impact on effective lens position, tilt or centration and, thus, refractive outcomes when compared with eyes having even grossly decentered and asymmetric capsulotomies.¹ This supports previous retrospective analysis.²

There is no strong clinical evidence to support an improvement in refractive outcomes when comparing the results of femtosecond laser-assisted cataract surgery (FLACS) vs. manual surgery, and the rhexis size and shape appear to have no significant bearing on clinical outcomes. Early FLACS proponents suggested a femto-created rhexis was stronger and safer than one created manually. However, scanning electron microscopy (SEM) studies have demonstrated repeatedly that the laser-created rhexis is markedly inferior to one created by manual tear and is characterized by “[a] zipper-like jagged edge, marred by postage-stamp perforations and aberrant pulses which are strikingly different than the smooth edge created manually.”³ The same investigators found that the “micro can opener” pattern seen through a SEM was associated with a 15-times higher radial tear-out rate during a femto-performed surgery than in manual tear cases. This finding was consistent with three different laser platforms.3 The laser-created rhexis, which is more prone to tear-out in routine cases, is more of a concern in complex cases in which capsular retractors and sutured capsular tension segments may be required due to stress on the anterior capsule during these maneuvers.

Day-one status post-femto-free phaco for a dense 3++ NS cataract. Patient has a previous cornea transplant with an extremely low cell count (less than 500) yet has a crystal clear and compact cornea the day after surgery.
COURTESY STEVE SAFRAN, MD

Now, new concerns exist regarding postoperative inflammation related to increased prostaglandin release associated with laser rhexis formation. A study by Schulz et al. found higher levels of aqueous humor prostaglandins associated with FLACs specifically related to laser formation of the anterior capsulotomy and concluded that “anterior laser capsulotomy stimulates prostaglandin release.”⁴ Another study showed a higher grade of inflammation and apoptosis in the central area of femtosecond laser capsulotomies compared to manual continuous curvilinear capsulorhexis.⁵ The significance of these findings will be determined over time, but there is little reason to suspect that increased inflammatory mediators related to the use of the laser can result in anything beneficial for the patient.

Cost and efficiency

Femtosecond lasers increase the cost and time of a routine cataract case. Laser purchase cost, click fees and maintenance fees increase the cost of each procedure by an amount that is roughly equivalent to the surgeon’s total fee for the procedure.⁶

Also, performing FLACS takes more time. A recent study showed that the average surgeon took 11.6 minutes to 13.4 minutes longer per routine case with FLACS.7 Another study showed that “Even with generous assumptions for improvements in visual outcomes and reduction in complications rates over phacoemulsification, femtosecond laser-assisted cataract surgery fails to reach the threshold of cost effectiveness in current Australian or U.S. dollars.”⁶

Since FLACS costs more in time and money per case, who pays for it? It is not legal in the United States to charge Medicare patients extra for using a femtosecond laser to perform covered steps in the cataract surgery. Thus, surgeons tie laser use to performing cornea-relaxing incisions to treat astigmatism to underwrite the cost of using the laser for the remaining steps in the cataract procedure. Most surgeons’ financial access to FLACS hinges on charging a significant premium for these incisions despite a lack of any studies that show they are safe and effective when performed in combination with cataract surgery. For patients with significant astigmatism we have better options, such as toric IOLs and laser vision correction.

Patient selection limitations

It may be difficult or impossible to use the laser on patients with miotic pupils, and it appears femtosecond-laser use makes pupils constrict. A recent study showed that the pupil comes down an average of 29.7% in surface area during femto fragmentation.⁸ Another study looking at more than 4,000 cases using the Catalys Precision Laser System (AMO) showed a five-times greater need for pupil-expansion devices in FLACS versus manual cases despite using the same pharmacologic regimen.⁹ Schultz et al. related increased prostaglandin release during femtosecond laser created rhexis formation as the main cause of miosis associated with FLACS.⁴ In addition to the increased risk of anterior capsule radial tear outs associated with a femto-created rhexis, there may be a higher risk of posterior capsular rupture in patients with polar cataracts when using FLACS, and using the laser in patients with a history of silicone oil in the eye involves a risk of an incomplete capsulotomy.^10,11

Specular microscopy showing extremely low endothelial cell count prior to cataract surgery that is virtually unchanged after femto-free phaco. Cell count and morphology look the same before and after cataract surgery.
COURTESY STEVE SAFRAN, MD

Patient selection limitations

With femto surgery, patient selection becomes more restrictive compared to manual surgery. Besides pupil size, the presence of a cornea opacity and/or loss or lack of clarity could interfere with laser transmission and lead to incomplete capsulotomy or fragmentation. If the patient has a deep-set eye or small palpebral fissure, it may preclude the laser’s safe docking. If the patient cannot fixate or cooperate during the laser portion of the procedure, there may be a break in treatment. Other complications have been unique to femtosecond-laser use, such as laser treatment of the endothelium or cornea stroma and perforation during OCT-guided relaxing incisions.^12-14

Conclusion

To consider adopting a new technique or device that increases procedure time, cost and complexity while introducing new and unique complications related to its use, I need compelling evidence of benefits to offset these increased costs and risks. Current clinical evidence does not support FLACs and in fact argues effectively against its use. OM

Steve Safran, MD, is on staff at Capital Health System, New Jersey Surgery Center and Robert Wood Johnson University Hospital in Hamilton, N.J. He is a fellowship-trained cornea specialist. Email him at safran12@comcast.net. The author has no relevant financial disclosures.

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