BREAKING THE LENS INTO QUADRANTS
By Eric D. Donnenfeld, MD
Laser-assisted cataract surgery is relatively new, but it has evolved considerably over the past 3 years and now has a prominent place in cataract surgery throughout the world. Initially, I attempted to maintain my standard phaco technique, but I subsequently recognized that major changes were needed for me to take full advantage of the potential of laser-assisted cataract surgery with the LenSx Laser System (Alcon) and to minimize complications.
Below I explain changes I made to my lens fragmentation and cataract extraction techniques. For a detailed overview of all changes to my laser-assisted phaco technique, see “How Laser Cataract Surgery Has Changed Our Phaco Technique,” in the January 2014 issue of CRST US (pages 37-38).
Division of the nucleus. My laser fracture technique involves creating two concentric circles of 4.5 and 2.5 mm along with an X pattern bisecting the lens. This pattern allows me to easily break the lens into quadrants. I sculpt the central doughnut I have created with the laser to make a hole in the center of the nucleus.
In the past, I split and then chopped the lens with a standard chopper. I now employ a chopper with an arc that fits nicely into the doughnut hole created in the lens (Donnenfeld Chopper; Katena Products, Inc.) to increase the contact area between the lens and the instrument (Figure 1). I further split the lens with the phaco probe to create quadrants that divide more easily. The larger surface area of the circular chopper provides a greater contact area for soft nuclei, which can sometimes be the most difficult lenses to separate.
Cataract extraction. In standard phacoemulsification, I use peristaltic vacuum to hold the nucleus, which requires full occlusion of the tip. With the use of the femtosecond laser, I find that the quadrants are mostly free-floating. In my experience, the venturi mode brings the lens nucleus to the center without the need for full occlusion, which makes quadrant removal extraordinarily rapid.
With the adoption of laser-assisted cataract surgery, I have changed every aspect of my phaco technique, including the steps outlined above. In so doing, I find that I have increased the safety of cataract surgery, and I hope that the techniques I have described will make adopting this technology easier for other surgeons.
Eric D. Donnenfeld, MD, is a Professor of Ophthalmology at NYU and a trustee of Dartmouth Medical School in Hanover, New Hampshire. Dr. Donnenfeld states that he is a consultant to Abbott Medical Optics Inc., Alcon, Bausch + Lomb, and Katena Products, Inc. Dr. Donnenfeld may be reached at tel: +1 516 766 2519; e-mail: ericdonnenfeld@gmail.com..
PEARLS TO REDUCE PHACO TIME
By Detlef Holland, MD; and Ludger Hanneken, MD
Phacoemulsification is safe and predictable, but, even in the most experienced hands, not all capsulorrhexes are perfectly centered and sized. Optimal capsulorrhexis parameters are crucial for ideal IOL position and to avoid tilt and decentration. Additionally, they allow the effective lens position to be calculated more exactly.
Posterior capsular rupture (PCR) and vitreous loss can also occur during phacoemulsification, especially throughout a surgeon’s learning curve, and endothelial cell loss can result from the maneuvers required in the procedure.
Although the potential complications of phacoemulsification are relatively rare, we believe that laser-assisted cataract surgery has the prospect to further enhance surgical reproducibility and, therefore, safety. To date, we have performed cataract surgery with the help of a femtosecond laser in more than 550 patients in Kiel, Germany, and about 300 patients in Cologne, Germany. In both centers, we use the LensAR Laser System (LensAR, Inc.).
The 3D-Confocal Structured Illumination (3D-CSI) imaging system of the LensAR uses Scheimplug technology to create a perfect reconstruction of the anterior segment that, in most cases, is accomplished automatically. Only in white or brunescent cataracts can the posterior capsule not be detected, and therefore the system switches to a reduced treatment zone. Laser capsulotomy will still be done automatically. Additionally, the laser measures and automatically compensates for lens tilt, reducing the risk of PCR during lens fragmentation.
At our centers, we use the laser for capsulotomy, lens fragmentation, clear corneal incisions (CCIs), and, if astigmatism correction is required, arcuate incisions. The laser provides a wide range of patterns for lens fragmentation, and each pattern can be individually adapted depending on the cataract grade (Figure 2). In soft lenses and brunescent cataracts, only two-plane chops can be performed (Figure 3).
Soft lenses do not require more chops for later aspiration, and in brunescent cataracts this mode helps greatly in later chopping maneuvers. In grades 2 and 3 cataracts, denser patterns can be used to soften the nucleus as much as possible. The more the lens is softened, the more that phaco time can be reduced. The LensAR system can fragment the complete central and mid-peripheral nucleus into cubes without creating excessive gas bubbles. Changing to maximum vacuum during aspiration—a deviation from our traditional phaco technique—helps to reduce phaco time, frequently to nearly zero, maximizing the benefits of the femtosecond laser for the entire cataract procedure.
Generally, it takes around 2 minutes for docking, scanning, capsulorrhexis, and lens fragmentation. When CCI and relaxing incisions are also performed with the laser, the procedure takes an additional minute. Although we both typically use a 2.2-mm incision, we have also performed a successful series of 1.8-mm incisions with the OS3 phaco system (Oertli) in Kiel and with the Stellaris Vision Enhancement System (Bausch + Lomb) in Cologne
Chopping and cracking the laser-fragmented nucleus is quick and easy because, in many cases, the fragmented nucleus can be aspirated without any additional phaco energy due to the high vacuum. When required, the cortex is aspirated with a mono- or bimanual technique. Mastering the aspiration phase can require a short learning curve. During IOL implantation, the capsulorrhexis is resistant and always leads to perfect overlapping of the optic.
Incorporating laser-assisted cataract surgery has helped each of us to reduce our total phaco time. In Kiel, the average phaco time is 1.9 seconds with the LensAR (average cataract grade, 2.4) and 3.7 seconds using a standard phacoemulsification technique (average cataract grade, 2.1). Additionally, endothelial cell loss with laser-assisted cataract surgery is approximately 3.8%, compared with 6.8% for standard phacoemulsification. These parameters will likely decrease further when we are even more acquainted with the laser technology.
Detlef Holland, MD, is a cataract and refractive surgeon at the Augenklinik Bellevue in Kiel, Germany. Dr. Holland states that he has no financial interest in the products or companies mentioned. He may be reached at e-mail: d.holland@augenklinik-bellevue.de.
Ludger Hanneken, MD, practices at Sehkraft Augenzentrum in Cologne, Germany. Dr. Hanneken states that he has no financial interest in the products or companies mentioned. He may be reached at e-mail: hanneken@sehkraft.de.
STRIVING FOR ZERO ULTRASOUND
By Edoardo Ligabue, MD; and Cristina Giordano, OD
The objective of cataract surgery with femtosecond laser assistance is to reduce the number of surgical maneuvers in an effort to make the procedure safer and more repeatable. In our experience, the most important starting point in this journey is selecting the laser fragmentation pattern. Using the Victus femtosecond laser (Bausch + Lomb Technolas; Figure 4), we have been able to standardize our energy selection and develop a nomogram for nucleus fragmentation.
In order to determine the required level of laser energy for nucleus fragmentation, we evaluated nucleus densitometry under a dilated pupil with the Sirius-CSO Scheimpflug camera (Costruzione Strumenti Oftalmici; Figure 5) and anterior corneal surface curvature gradient in 100 eyes undergoing laser-assisted cataract surgery. We transferred these values to our nomogram, the Ligabue-Giordano Femto Cataract Nomogram, to automatically select the fragmentation energy required for this step of the Victus procedure. Changing the percentage value of the nucleus densitometry gives us the fragmentation energy value in nanojoules.
Our nucleus fragmentation pattern is a combination of four radial cuts with a diameter of 7,500 μm and two circular cuts with diameters of 3,000 μm. After the laser treatment, we prepare to aspirate the nucleus with the Stellaris Vision Enhancement System through a 2.2-mm CCI. The anterior capsule is opened with rhexis forceps, and hydrodissection is performed using a standard flat hydrodissection cannula.
Next, we proceed with nucleus prechop using a prechopper designed for small-incision cataract surgery (Janach). The prechop phase is crucial: It allows us to obtain four complete quadrant divisions without using the ultrasound handpiece (Figure 6). This step is made easier by the radial cuts performed earlier by the Victus femtosecond laser, with the depth of fragmentation set to maintain a safety zone of 300 μm from the posterior capsule.
If the nucleus grade is between 1 and 3 (Lens Opacities Classification System III) and has a densitometry percentage value between 10% and 20% (Sirius densitometry evaluation), we use a modified I/A handpiece with a sharp, straight tip. We set the Stellaris on the I/A program (maximum vacuum with fast response) and start aspirating the quadrants (Figure 7). The trick is to capture the nucleus pieces in the periphery, where the material is softer. To aid in nucleus aspiration, we use the tip of a custom nucleus manipulator spatula (Janach). The procedure is fast and allows us to work in the safe center zone of the anterior chamber, where manipulations to the nucleus are made far from the endothelium and the posterior capsule.
If the cataract is dense (more than grade 3) and the densitometry percentage is more than 20%, we use an ultrasound handpiece with a standard 30° tip. In these cases, it can be useful to change the fragmentation pattern and program a pattern of six radial cuts (no circular cuts), as nucleus division with radial cuts alone reduces ultrasound energy considerably.
Use of the correct laser energy power and laser fragmentation pattern makes the phacoemulsification phase of cataract surgery easier and quicker than it is with a conventional phacoemulsification technique. The most important advantage of laser lens fragmentation is the ability to reduce or eliminate the need for ultrasound during the surgical procedure. After 1.5 years of experience with the Victus, we are happy to say that, in our best cases, we have achieved zero ultrasound. In our opinion, this is the real goal for which to strive, because it safeguards the integrity of the endothelium during surgery.
Edoardo A. Ligabue, MD, is the Chief of the Cataract and Refractive Department of the Ophthalmic Center at the Centro Diagnostico Italiano in Milan, Italy. Dr. Ligabue states that he has no financial interest in the products or companies mentioned. He may be reached at e-mail: edoliga@tiscali.it.
Cristina Giordano, OD, practices at the Centro Diagnostico Italiano in Milan, Italy. Dr. Giordano states that she has no financial interest in the products or companies mentioned. She may be reached at e-mail: applysrl@virgilio.it.
THE FEMTO CHOP TECHNIQUE
By Wendell J. Scott, MD
I began my career performing extracapsular cataract extraction with IOL implantation in 1984. Phacoemulsification was a major revolution then, and I believe laser-assisted cataract surgery is the next disruptive technology that will change the way we think about—and perform—cataract surgery. Since starting with this cataract surgery technique in March 2013, I have performed more than 1,400 laser-assisted cases. In reviewing the last 100, 98% were performed with little to no phaco energy (effective phaco time with the Ellips EFX phaco tip [Abbott Medical Optics Inc.], less than 2 seconds) and 84% with zero phacoemulsification.
We have two Catalys femtosecond lasers (Abbott Medical Optics Inc.) that are located in two operating suites. This allows one surgeon to use both suites, improving the efficiency of patient flow. The patient is taken to the operating room and transferred to the Catalys integrated bed.
A fenestrated drape is placed over the eye without isolation of the lashes; a speculum is not used. The laser patient interface is applied, vacuum engaged, and balanced saline solution instilled into the liquid interface. The patient is rotated under the laser and docked into position, and the laser treatment is applied.
My laser settings have evolved over time. The method by which the Catalys laser treatment is guided by optical coherence tomography (OCT) is a key difference between this and other systems, as it allows the surgeon to be more accurate and confident in the treatment. Currently, I use a 4.9-mm capsulotomy with a 0.7-second treatment time (Figure 8). With this capsulotomy setting, the capsule edge is smooth, and no irregularities are present. The laser pattern segments the lens into quadrants, and the lens is treated with a grid pattern. This pattern facilitates removal of the lens by aspiration alone. The total time that vacuum is applied for the OCT and treatment is usually 1.5 to 2.0 minutes, varying with the cataract density. A short treatment time lessens the chance that patient movement will affect the treatment.
After laser treatment, the integrated bed is rotated out and the microscope rotated in over the patient. After the eye is prepped, it is irrigated with dilute betadine 0.25%. A 25-gauge needle on a 1% lidocaine syringe is used to make a paracentesis, and lidocaine is instilled into the anterior chamber. The needle is used to perform a central dimple-down technique, confirming the free-floating status of the capsule. Healon (Abbott Medical Optics Inc.) is instilled into the anterior chamber through the paracentesis. A 2.4-mm keratome blade is used to place a temporal incision, and additional Healon is instilled directly over the lens, lifting the capsule away from the lens surface.
A bimanual cracking procedure is performed using a Koch Stop and Chop manipulator (Bausch + Lomb Storz) through the paracentesis and a Bechert fork through the main incision. The chop instrument is placed near the border of the capsulotomy nasally, and the fork is placed temporally (Figure 9A). Both are placed in the linear soft segment of the laser-treated lens and drawn toward each other centrally (Figure 9B). As they meet, each instrument is pushed laterally, splitting the lens and releasing gas centrally through the cracked lens. Next, with the Bechert fork remaining in a central position, the chopper is positioned near the capsulotomy in a vertical position and drawn toward the Bechert fork, further splitting the lens into quadrants. This bubble-chop technique divides the lens into quadrants, releases gas centrally, decreases tension on the capsular bag, and does not require hydrodissection. The eye is rinsed with dilute betadine 0.25%.
Using the WhiteStar Signature unit (Abbott Medical Optics Inc.) in venturi mode, a 21-gauge curved phaco tip (Laminar Flow 30º Curved; Abbott Medical Optics Inc.) with a yellow Laminar irrigation sleeve designed for 20-gauge needles is used along with the Koch Stop and Chop manipulator to aspirate the cataract. The 21-gauge needle with the 20-gauge sleeve maximizes flow and stability of the anterior chamber.
With the vacuum on 600 mm Hg surgeon control, the tip engages the first section of lens and the chopper assists by extending to the posterior periphery and lifting the periphery of the quadrant forward to the center area. Successive quarters are brought forward in this way. If necessary, the maximum vacuum is reduced for the last portion of lens aspiration. Occasionally, phacoemulsification energy is needed. In these cases, the power is set at 1, which is an adequate level for almost all cataracts. The eye is rinsed with dilute betadine 0.25%.
Proceeding in venturi mode for irrigation/aspiration, the cortex is removed using a polymer tip (0.3-mm Polymer Tip; Alcon), with the subincision cortex being removed first. The capsule is vacuumed, and Healon is instilled to fill the capsular bag and anterior chamber. The most common lens implanted is the Tecnis ZCB00 monofocal one-piece acrylic IOL (Abbott Medical Optics Inc.), but I also implant Tecnis multifocal and toric lenses, AcrySof ReStor multifocal and toric lenses (Alcon), and the Crystalens (Bausch + Lomb). After IOL implantation, the Healon is aspirated, the incision and paracentesis are hydrated, and additional hydration with vancomycin is performed. The eye is rinsed with dilute betadine 0.25%, and brimonidine 0.2% drops are instilled. A clear shield is placed over the operative eye, and the patient is taken to the outpatient recovery area.
Wendell J. Scott, MD, practices at Mercy Eye Specialists in Springfield, Missouri. Dr. Scott states that he has no financial interest in the products or companies mentioned. He may be reached at tel: +1 417 820 9393; e-mail: Wendell.Scott@mercy.net.
