Technology upgrades strengthen foothold of femto in ocular surgery
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Over the past decade, femtosecond laser technology has matured in both corneal and cataract applications to be more refined and user friendly, creating new opportunities for minimally invasive procedures.
“Femto has now a strong foothold in corneal surgery and LASIK, and with various names, the SMILE procedure, introduced by Zeiss, has spread worldwide with lots of literature supporting the value of it. Finally, in cataract surgery, the femto has a strong foothold at least in North America,” William W. Culbertson, MD, said.
Source: Dagny Zhu, MD
Companies have been working on refinements of the technology, and further improvements are underway.
“There have been innovations aimed at improving patient comfort, the efficiency of the procedures as well as laser cut quality and refractive accuracy. There is also a move toward multipurpose machines that combine different procedures, with the benefits of a smaller footprint and improved workflow,” Dagny Zhu, MD, said.
More comfortable, safer surgery
In cataract surgery there has been significant progress in terms of making the procedure more comfortable and safer. The current “no corneal touch” and liquid interface docking systems cause lower IOP increase and less subconjunctival hemorrhage and make the delivery of the treatment more comfortable, easier and safer.
“Lensar in particular has upgraded its patient interface device to fit more eyes. It has an elliptical-shaped option that is a little narrower and deeper and achieves better suction in patients with smaller palpebral fissures or deeper orbits, which were a problem in the past with femtosecond laser surgery,” Zhu said.
In terms of efficiency, all of the femtosecond lasers are moving toward faster imaging acquisition and faster delivery of the laser treatment, leading to enhanced safety without any loss of suction.
“And the quality of the capsulotomy is also better with the fine-tuning of the laser pulses, that is, lower pulse energy and higher frequency,” she said.
OSN Cataract Surgery Board Member Audrey R. Talley Rostov, MD, has used the LenSx (Alcon), the Victus (Bausch + Lomb) and the Catalys (Johnson & Johnson Vision), and she is now using the Lensar. In her view, capsulotomy is where the Lensar shines. The 3D-CSI diagnostic system automatically generates the data for the size, shape and position of the capsulotomy according to the eye’s real anatomy.
“In addition to making perfect custom capsulotomies, the software marks them with little notches so that you can properly orient your toric IOL. And it has automatic iris registration, with the ability to upload your data from whatever system you use, Pentacam (Oculus) or Cassini. It’s extremely accurate and worry-free,” she said.
The Catalys also makes little marks in the stroma, and all lasers make corneal relaxing incisions for the correction of low astigmatism.
“I really like these features of the femtosecond laser for more complex cases, like for cornea transplant patients. If these patients have astigmatism, you can use a toric lens and make arcs within the graft, achieving a very nice result,” Talley Rostov said.
The Lensar device has several built-in nomograms for arcuate incision astigmatism correction, Zhu said.
“You can choose whatever nomogram you like to start with and fine-tune it over time based on your own outcomes,” she said.
Down to the nucleus
Lens densitometry, which grades nuclear density objectively, can be implemented with Lensar’s advanced imaging system.
“Cataract densitometry allows to preprogram patterns for lens fragmentation according to the cataract grade. Phaco energy is therefore optimized to reduce the potential for inflammation and cell loss,” Talley Rostov said. “If you have a patient with Marfan syndrome, trauma or lens dislocation, you have the ability to center the capsulotomy on the lens rather than the pupil center. And the nice thing is that you can also do it on the fly. You program your usual capsulotomy and can enlarge it when you visualize the lens if the cataract is denser than expected.”
The Keranova FemtoMatrix laser system uses a unique photonic technology for customized OCT-guided photoemulsification of the lens. The finely diced nucleus is then aspirated with no use of ultrasound.
“That was the way cataract surgery for laser started. The idea was to soften the lens enough to aspirate it instead of using phaco energy. The Keranova laser is able to cut the lens into tiny cubes, using just the right amount of energy and number of laser spots in each area, and making almost an emulsion of the lens that can be aspirated. This seems to be quite successful with soft lenses. If it will be possible for harder lenses, that remains to be seen,” Culbertson said.
Pairing laser and phaco in one unit
Surgeons in the U.S. are looking forward to the new Ally adaptive cataract treatment system (Lensar), the first platform to combine femtosecond laser and phacoemulsification technology in a single system. The FDA cleared the system in June.
“No longer will you need to move the patient from the femtosecond laser into the OR and use a different phacoemulsification machine. You can actually have the patient stay in one bed and complete the procedure from the femtosecond laser portion to the whole cataract surgery with phaco,” Zhu said.
The benefits are obvious, she said: a smaller footprint, a solution for surgeons who have limited space, improved workflow, ease in terms of patient transportation, and the possibility to complete the procedure under sterile conditions from beginning to end.
“The image acquisition and the treatment time are a lot faster, about half compared to the Lensar now. And the smart AI interface allows the different parts of the system to speak to each other and fine-tune the treatment depending on the information acquired,” she said.
In addition, technicians will save time because they will be trained on one platform rather than on two different devices.
Pairing the laser with a built-in phaco unit may be suited for more office-based cataract surgery, working great for some business models but causing a challenge for others, according to Bennett Walton, MD, MBA.
“If you have more than one operating room, you might want one of those machines in each room. Based on the patient flow and potential cost, practices will need to look into their business models to see how much that helps, if at all,” he said.
From manual to femto
Walton has been working since 2015 in private practice with Stephen Slade, MD, the first surgeon to perform laser cataract surgery in the U.S.
“The whole practice benefits from his legacy of innovation, and in our practice, many cataract cases are femto,” he said. “Manual surgery is still offered to patients who do not choose femto, but many do when we explain the benefits of it, especially in the context of astigmatism correction and presbyopia correction, which will give them greater independence and potentially a greater range of vision.”
His advice to surgeons who are considering a switch to femtosecond cataract surgery is to think of it as a separate procedure that requires a different mindset and separate techniques with separate instruments.
“Think critically about which instruments allow the most central placement within the eye to reduce being near the capsule and which fluidics settings allow the maximum safety and reduction in phaco energy so that everything can be as central in the eye as possible at the appropriate anteroposterior plane. Think in terms of saving as many endothelial cells as possible and staying away from the capsule,” Walton said. “Surgeons who simply use the femto but do their same divide-and-conquer or chop techniques after softening the lens won’t maximize the benefits of the laser.”
Improved quality and speed in LASIK
All femtosecond lasers are continuing to improve the quality and the speed of LASIK flap creation.
“The faster you can do the procedure, the safer it is, the less likely you are to lose suction, and the more comfortable it is for the patient,” Zhu said. “The femtosecond portion is the least comfortable and scariest part of the procedure because the patient experiences pressure during the application of suction and the vision turns dark. So, a lot of the femtosecond lasers are headed for quicker flap creation, higher frequency pulse spots with lower energy, better quality flaps and a gentler interface to reduce the amount of pressure needed to dock on the eye.”
The Ziemer LDV Z8 combines the technologies for refractive, cornea and cataract procedures, which is an advantage in terms of reduced footprint, and it is nice to only have to purchase one machine, according to Zhu.
“I use the Ziemer mostly for LASIK, and I think it creates the best quality flaps. It’s just a workhorse,” she said. “The high-frequency, low-energy technology creates excellent quality flaps with smooth stromal beds, very neat and easy to lift.”
One feature added to the system is that instead of manually docking the laser on the patient’s visual axis, the centration of the treatment is fine-tuned on the screen after docking. Another advantage over other femtosecond lasers is the compact size.
“It has the smallest footprint of all the femtosecond lasers, and it comes on wheels, so you can move it from one room to another. It’s super compact, and it has an adjustable arm, very flexible, that you can maneuver over the patient’s eye. I keep the patient on the bed of my Allegretto EX500 (Alcon) and the Ziemer is right next to it, and I can easily just slide the arm on top of the patient’s eye to complete the treatment rather than having to switch beds,” Zhu said.
Lenticule extraction gaining ground
Refractive surgery in the U.S. is still dominated by LASIK, but SMILE is gradually gaining popularity.
“SMILE’s market share has grown dramatically in eastern Asia with the high myopes and is quite large in Europe. Our clinical experience is that on average patients take longer than with LASIK to get to their best vision but still do very well, and the results are excellent when compared to LASIK at 6 months,” Walton said.
A number of companies are working on improvements for lenticule extraction refractive surgery, such as faster speed, smaller footprint, enhanced resection profile and centration, and cyclotorsion compensation.
“Zeiss introduced last year the new VisuMax 800, not yet available in the U.S. It is an upgraded and updated system, more all purpose, that does everything at a more refined level, more comfortable for the surgeon and the patient,” Culbertson said.
The system features computer-controlled centration before the patient’s eye is docked, as well as digital recalculation of the treatment pattern if cyclotorsion occurs. The laser is fast and enables the surgeon to cut the lenticule in approximately 10 seconds.
In the U.S., Johnson & Johnson Vision has been working on a similar laser for intrastromal resection.
“The machine is called Elita. It has gone through the preclinical stages, and a clinical trial in humans is currently being set up. I know from personal experience that resection is easier and better, that the system has rotational identification and compensation, and that accuracy is down to 3 µm of depth of the resection. The laser aims at reduced pulse energy and faster speed and does resection by quick multiple passes,” Culbertson said.
Schwind has also developed a femtosecond laser for minimally invasive lenticule extraction, the ATOS, not yet available in the U.S.
“It has rotational cyclotorsion compensation, intelligent centration and an innovative, more comfortable patient interface. Ziemer also has a machine, a derivative of the existing machine with an articulated arm, called CLEAR — corneal lenticule extraction for advanced refractive correction,” he said.
“I love doing SMILE. I started doing it a few years ago, just before the pandemic, and my results have been amazing,” Talley Rostov said. “It has become my laser vision correction procedure of choice for myopia from –1.75 D to –10 D and up to about 2 D of astigmatism. It is less invasive than LASIK, there’s no flap, and there’s also less dry eye. I am looking forward to having the VisuMax 800 here. I have tried it in a nonclinical setting, and it is amazing. When I came back to use my own VisuMax, it felt as if it was taking so long as compared to the 800.”
Keratoplasty techniques
Talley Rostov has also been working on innovative lamellar keratoplasty techniques, such as femtosecond laser lamellar keratectomy for granular dystrophy.
“I measure the depth of the granular dystrophy with OCT. Then I create a deep LASIK flap with the VisuMax at about 190 µm and simply cut the flap off, debulking most of the granular dystrophy. The epithelium grows over it and refraction doesn’t change, but the patient can see better. I expect the granular deposits will come back at some point and the patient will need a transplant, but at least I can delay it, especially for younger patients,” she said.
Talley Rostov is working with Marjan Farid, MD, on a project to perfect deep anterior lamellar keratoplasty with femtosecond technology.
“We are working with the VisuMax on eye bank eyes, and the precision of the cuts is unbelievable. Intraoperative OCT helps you to see where you are and visualize the cut, which is so perfect and reproducible. Cleaner cuts are likely to lead to better outcomes and potentially less astigmatism,” she said.
Talley Rostov had the privilege to be guided through her first cases of femtosecond-assisted corneal transplantation by Roger Steinert, MD.
“We used the IntraLase at the time, which was a good machine but did not have the refined quality of VisuMax. The IntraLase was like your good basic model Kia; the VisuMax is like your BMW or Porsche,” she said.
Top qualities
For refractive surgery, Walton has used both the WaveLight FS200 (Alcon) and the VisuMax for LASIK and the VisuMax for SMILE.
“Both are excellent. The low suction of the VisuMax is very comfortable, and the applanation of FS200 is very reliable. I find the FS200 a little more user friendly for difficult patients, it requires less cooperation, and it also allows for software centration of the flap, whereas the VisuMax requires good docking skills. I look forward to the VisuMax 800 and its beautiful engineering, and it will make the SMILE procedure easier and the patient flow smoother for our practices,” he said.
As part of her training at Bascom Palmer Eye Institute, Zhu has had hands-on experience with every femtosecond laser platform.
“On the LASIK side, I have used the FS200, the VisuMax, the IntraLase and the Ziemer. The VisuMax is the gentlest, with the least pressure increase during docking. So, the patients don’t experience that blackout vision that they do with almost every other femtosecond laser. On the cons side, you have a higher chance of breaking suction. So, when you have nervous patients, you have to talk to them to calm them down and walk them through it more so than with other lasers. The Ziemer has the smallest footprint of all the femtosecond lasers, it is very easy to use and roll around the clinic, and I think it produces excellent quality flaps. I rarely have any issues with partial flaps or buttonholes. On the cataract side, the Lensar and the Catalys have a similar fluid docking interface, very gentle on the eye, the least likely to cause hemorrhage and trauma to the eye,” she said.
Culbertson has also used multiple platforms and was involved in the development of the Catalys laser and early development of the IntraLase. He uses femtosecond technology to do all kinds of corneal surgery, cataract surgery, astigmatic keratotomy, keratoplasty, channels for intracorneal rings, and lamellar pockets for corneal tattooing in patients with iris defects.
“I think that femtosecond laser is a worthwhile investment and a practice builder, but first of all surgeons have to believe in the laser themselves. They have to understand that it can be a financial advantage in several different ways,” he said.
“The laser technology resonates well with patients,” Walton said “However, we want to make sure that patients understand it is still the skill of the surgeon that gives them the good outcome. Laser alone doesn’t do it.”
- References:
- Agarwal K, et al. Semin Ophthalmol. 2021;doi:10.1080/08820538.2021.1890792.
- Fuest M, et al. Taiwan J Ophthalmol. 2021;doi:10.4103/tjo.tjo_12_21.
- Gogri PY, et al. J Cataract Refract Surg. 2021;doi:10.1097/j.jcrs.0000000000000400.
- He L, et al. Curr Opin Ophthalmol. 2011;doi:10.1097/ICU.0b013e3283414f76.
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- Kanclerz P, et al. Eur J Ophthalmol. 2021;doi:10.1177/1120672120922448.
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- Moshirfar M, et al. Small Incision Lenticule Extraction. 2021. StatPearls Publishing.
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- For more information:
- William W. Culbertson, MD, can be reached at Bascom Palmer Eye Institute, 900 NW 17th St., Miami, FL 33136; email: wculbertson@med.miami.edu.
- Audrey R. Talley Rostov, MD, can be reached at Northwest Eye Surgeons, 10330 Meridian Ave. N., Suite 370, Seattle, WA 98133; email: atalleyrostov@nweyes.com.
- Bennett Walton, MD, MBA, can be reached at Slade & Baker Vision, 3900 Essex Lane, Suite 101, Houston, TX 77027; email: drwalton@visiontexas.com.
- Dagny Zhu, MD, can be reached at Hyperspeed LASIK, 17980 Castleton St., Rowland Heights, CA 91748; email: dagny.zhu@nvisioncenters.com.
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