Femto-Assisted Cataract Surgery: A Glimpse of the Future?

This technology has the potential to radically transform our cataract practices. Should it?

BY Uday Devgan, MD

Femtosecond lasers are being touted as the next great leap forward in cataract surgery but, as with any radical change to our practices, many questions remain: Does this technology truly improve cataract surgery? Is the refractive accuracy better? Is the safety profile significantly elevated compared to existing technologies? Are there additional complications or issues with using this laser? How does a surgeon incorporate this new technology in the practice? And the elephant in the room: what is the best business model to seek payment for use of this laser?

More than 15 years ago, femtosecond lasers were first described as a surgical tool. I have just begun to use the assistance of a femtosecond laser for some of my cataract surgery patients and I think this new technology holds promise. However, just like with any new technology, there is a learning curve and a new set of potential complications.

Potential Benefits

Many parts of cataract surgery can be performed with the femtosecond laser, including the capsulorhexis, corneal incisions and division of the lens nucleus (Figure 1). Precise delivery of laser energy is made possible by the guidance of an OCT image and input from an experienced surgeon. Currently in cataract surgery, the femtosecond laser is used to replace a manual part of our existing phacoemulsification procedure with a machine in the hopes of improving precision and, therefore, results.

Figure 1. The femtosecond laser treatment for cataract surgery is shown in this plastic polymer. The blue outline shows the temporal main incision and the paracentesis a few clock hours away. The green arrow points to the capsulorhexis and the yellow arrows show the arcuate incisions for astigmatism management. The red arrows show the complex delivery pattern for nucleus division, with a cruciate pattern for dividing the lens nucleus into quadrants and a central cylindrical component to soften and debulk the apex of each quadrant to facilitate removal. The inset photo shows the depth of the incisions, with the capsulorhexis (green) being quite shallow compared to the nucleus division (red). COURTESY OF UDAY DEVGAN, MD

Similar to the patterns created when using a femtosecond laser for corneal transplantation, complex corneal incisions with intricate geometry can easily be created with the laser. This includes the main phaco incision and paracentesis as well as arcuate incisions for treatment of astigmatism. Having very precisely controlled incisions can help to provide a more accurate postoperative refractive state with regards to astigmatism.

In order to improve our spherical refractive outcomes, some surgeons have suggested that a laser-created capsulorhexis may provide a more predictable effective lens position for the IOL. While I agree that having a round, symmetric capsulorhexis with the anterior lens capsule overlapping the edge of the optic is important for accurate postoperative IOL position, data has yet to confirm that a machine-made capsulorhexis performs significantly better than one made by an experienced surgeon.

Many techniques have been developed to disassemble the lens nucleus, from divide-and-conquer to phaco chop. While some studies have shown that phaco chop allows reduced phaco energy use and better outcomes, the associated learning curve has deterred some surgeons from learning the method. With the femtosecond laser, the nucleus can be divided very easily into quadrants or other fragments within seconds. To further facilitate surgery, the laser that I am currently using allows for additional energy delivery into the central core of the nucleus in the form of cylinders. This additional treatment softens and debulks the apex of each quadrant so that the phaco probe can get a good purchase and more easily aspirate these lens pieces.

When astigmatism treatment is needed, corneal arcuate incisions can be challenging to perform manually since precise depth, position and arc length are the primary determinants of their effect. With the femtosecond laser, the specific corneal pachymetry for each eye can be measured and then a preset depth can be specified along with arc length and position. These incisions can even be performed in semi-attached segments, with the surgeon able to titrate the astigmatic relaxing effect in the postoperative period by selectively opening along the arc length.

Potential Complications and Limitations

With any new surgical technology or procedure, there is a distinct learning curve and an entirely new set of potential complications. Even experienced cataract surgeons will need to learn to dock the eye to the laser, interpret the anatomic images, adjust the laser parameters and safely deliver the energy. While the femtosecond lasers have been said by some to revolutionize the surgical process, the new machines also come equipped with complications that are specific to the technology. Take, for example, ultrasonic phacoemulsification. We learned to prevent corneal wound burns and fluidic surges — complications that were unique to phacoemulsification and not present in manual extra-capsular surgery. The same holds true for femtosecond lasers.

The accurate delivery of laser energy into the appropriate structures is how the femtosecond laser provides precise dissection of tissue for cataract surgery. Improperly placed laser energy can also be the source of complications. OCT imaging helps guide the laser energy and tailor the laser pattern for each individual eye.

Coupling the eye to the femtosecond laser is somewhat different across the various machine platforms, but one thing remains constant: the need to accurately align the eye. If the laser is misaligned by even a fraction of a millimeter, the energy delivery can be misdirected, with unexpected results. If the eye is tilted or skewed to one side, the accurate placement of laser energy is more difficult and a complication such as an incomplete capsulorhexis is possible (Figure 2). This is easily remedied by manually completing the capsulorhexis with forceps, while other alignment issues, such as an incorrectly placed incision or energy delivery into the posterior capsule, are not.

Figure 2. A tilted eye resulted in a partially completed capsulorhexis where only the right half of the anterior lens capsule was cut with the laser (Frame 1). Forceps are used to manually finish the left half of the capsulorhexis (Frame 2) which results in a normal, round, complete capsulorhexis (Frame 3). COURTESY OF UDAY DEVGAN, MD

Even with a perfectly cut capsulorhexis, there can be additional surgical challenges. When the laser cuts the capsulorhexis, it also neatly cuts the anterior cortical layer of the cataract. During our normal cortex removal with the irrigation-aspiration probe, we grab strands of anterior cortex in order to completely clean the capsular bag. However, since the anterior cortex is cut with the femtosecond laser, these strands are no longer present and we must resort to alternate techniques. I have found that using a diamond-dusted olive tip cannula to roughen the cortex along the undersurface of the anterior capsule helps create cortical strands, which facilitates complete cortex removal.

The patient interface for our femtosecond laser requires a period of suction which can last three minutes or longer. This is tolerated well in most patients, but it may cause a subconjunctival hemorrhage, particularly in patients who are taking systemic blood thinners. In addition, the rise in the intraocular pressure during suction may cause issues in patients with advanced glaucoma.

Using a femtosecond laser to perform parts of the cataract surgery requires additional time and this can slow down the flow in the surgery center. In our center, there are three eye operating rooms with the femtosecond laser placed in a separate room just before. For patients having the femto-phaco procedure, the first stop is the laser room. To ensure that our surgery center runs on schedule, we have allotted an extra 15 minutes for each femto-assisted case, though it typically requires less time than this.

When it comes to more challenging cases, such as patients with dense, white cataracts and small pupils, the femtosecond laser may not prove to be as useful. The capsulorhexis cannot be created if the iris is blocking the anterior lens capsule and the laser energy to divide the lens nucleus may not adequately penetrate a truly opaque lens.

Dealing with Intraocular Gas Bubbles

One of the expected side effects of femtosecond laser use is creation of gas bubbles within the tissue. In Figure 3, this issue presented as large bubbles in the anterior chamber, smaller bubbles around the capsulorhexis edge and larger gas pockets in and around the lens nucleus. This gas can help with performing a pneumodissection of the lens from the capsule, but it may also contribute to increased pressure and capsular block syndrome leading to posterior capsule rupture and a dislocated lens nucleus. Gently using a blunt instrument, like a small-gauge cannula, to lightly rock the lens nucleus allows much of the trapped air to come around the lens equator and into the anterior chamber. Most cases can then be performed without the need for hydrodissection with balanced salt solution. We can proceed directly to further splitting of the lens nucleus using a bimanual technique or Akahoshi-style pre-chopper. The freed lens quadrants can then be readily phaco-aspirated.

Figure 3. Intraoperative view of femtosecond laser incisions in cataract surgery made with Alcon’s LenSx. Note the presence of small gas bubbles under the anterior lens capsule and the larger, yellow-appearing gas pockets in and around the lens nucleus. COURTESY OF UDAY DEVGAN, MD

Cost Concerns

Femtosecond lasers are expensive — a high price for the machine, a costly maintenance contract and per-use fees add up quickly. The financial investment is likely one of the largest areas of concern for surgery centers deciding whether or not to take the plunge, especially when, as of right now, there is no additional reimbursement offered for cataract surgeries performed with the laser. Our surgery center prides itself in delivering the highest quality care while staying on the cutting edge of new technology. The surgery center members made the decision to purchase many new technologies over the years, such as coaxiallighted microscopes, multiple phaco platforms, intraoperative aberrometry, and now, the first femtosecond laser for cataract surgery in Los Angeles county.

The AAO and ASCRS recently issued guidelines for billing patients when using the femtosecond laser during their cataract surgery (see At Press Time on page 8). The bottom line is that any part of the cataract procedure that is covered cannot be separately billed to the patient. This means that whether a surgeon uses a $10 disposable steel blade, a $5,000 diamond keratome or a $500,000 femtosecond laser to create the corneal incision for surgery, the Medicare reimbursement is identical and the patient cannot be billed separately for this service. The same goes for extraction of the cataract, which can be done manually using an extracapsular technique, via phacoemulsification or with the femtosecond laser.

The only femtosecond laser procedures for which Medicare beneficiaries may pay out of pocket are refractive surgical techniques such as astigmatic keratotomy or limbal relaxing incisions. Even for patients who elect to pay out of pocket for a toric IOL or a presbyopia-correcting lens implant, they can only be charged a fee for the femtosecond laser if it is used in a refractive surgery procedure.

Effectively, this means that it is the surgeon’s responsibility to choose what he deems the best technology for his patients. Decades ago, when surgeons moved from doing manual extracapsular cataract surgery to phacoemulsification, the costs increased dramatically but the reimbursement, and even the CPT code 66984, remained the same. We are looking at the same predicament as we now begin to integrate the femtosecond laser into our cataract procedures.

Further Evolution of Technology

For the novice ophthalmic surgeon, performing a capsulorhexis and learning phaco-chop can be challenging. Having laser precision for these portions of the procedure could help a greener surgeon achieve better results. For routine cases, the femtosecond laser could make a good surgeon even better. For the highly experienced cataract surgeon, the benefits of these new lasers in their current iteration may be less pronounced.

Cataract surgery is one of the most rapidly evolving procedures in medicine, with modern-day techniques that are far better than older procedures. Our patients now benefit from a minimally traumatic surgery that takes just minutes, and can achieve excellent vision almost immediately. But even with the great cataract procedure we have today, I am confident that our technique, instrumentation and lens implants will continue to evolve. Using the femtosecond laser to refine cataract surgery may represent the beginning of this next era. With new IOL designs in the coming years, there may be a need to make a specific sized or shaped capsulorhexis, a posterior capsulorhexis or even a tiny capsulorhexis — this is where the femto may truly shine.

Figure 4a. Laser capsulotomy samples performed with the Catalys Precision Laser System, stained with trypan blue to demonstrate precision in size and shape. COURTESY OF OPTIMEDICA

Figure 4b. By contrast, manual capsulorhexes (also stained with trypan blue) demonstrate irregularity in size and shape. COURTESY OF OPTIMEDICA

Currently only about 1% of ophthalmologists in the US have access to a femtosecond laser for cataract surgery, but this number is expected to increase as more machines are delivered. These systems are in their infancy and the future likely holds faster, less traumatic and more accurate platforms. But lasers are just another instrument, like a blade or forceps. Surgery will still require a surgeon, because surgical judgment simply cannot be programmed into a laser or any other machine. OM

Uday Devgan MD is in private practice at Devgan Eye Surgery in Los Angeles and Beverly Hills, California. In addition he is Chief of Ophthalmology at Olive View UCLA Medical Center and Associate Clinical Professor at the UCLA School of Medicine. He can be reached at devgan@gmail.com or on www.DevganEye.com.