In Part 1 of this article on Femtosecond Lasers for Cataract Surgery, I began the discussion of my experience with the Catalys and LenSx systems. I compared the strengths and weaknesses of both devices for the first 4 components of the femtosecond laser procedure: User Interface, Patient Interface, Imaging and Analysis. In this part of the article I will continue with the 5th component—the laser itself, and then summarize my observations regarding the intraocular steps of the cataract removal.
After the system is set up, the patient properly docked, the eye imaged and the images analyzed for treatment planning, the final step of the femtosecond laser procedure is the actual laser treatment.
The Lasers
AMO’s Catalys Precision Laser System.
The laser incisions are more adjustable and are performed more quickly with the Catalys than with the LenSx. For example, the time to complete the capsulotomy is approximately 1.5 seconds with the Catalys vs. 5 seconds for the LenSx. Both systems are able to create a primary incision, side port incisions, and astigmatic incisions; however, the Catalys has more flexibility for these corneal incisions. Specifically, the LenSx cannot create side port incisions in the absence of a primary incision, cannot create multi-planed side port incisions, cannot create more than two side port incisions, and cannot create side port or astigmatic incisions within 15 degrees of other corneal incisions.
Alcon’s LenSx Laser.
Regarding lens fragmentation, the Catalys has the capability of creating a grid pattern that results in small aspiratable cubes. This significantly reduces and often eliminates the need for phacoemulsification during lens removal. Cutting such a pattern in the lens accounts for most of the treatment time with the Catalys. A similar fragmentation pattern may soon be available on the LenSx system but will probably add considerable time to the treatment. Both devices generate printable reports with information regarding laser energy and the various parameters for each laser cut. I find the Catalys report easier to read and more informative because it is formatted more clearly and lists the times for each laser cut as well as the total vacuum time, information that is not included in the LenSx report.
In terms of patient flow, both systems are about equal. The Catalys has an integrated bed requiring the patient to transfer back and forth from their gurney for the laser treatment, but this can be accomplished rather quickly. Although the patient remains on the gurney for the LenSx procedure, the time it takes for all the manipulations (i.e., adjust the gurney and patient’s head position, insert a lid speculum, sometimes remove the SoftFit contact lens from the patient’s eye, and remove the lid speculum) is similar to the time it takes a patient to transfer to an integrated bed.
Femtosecond Laser Surgery
Once the patient is in the operating room, some adjustments to standard cataract surgical technique are necessary. I also noted some differences in the laser cuts and ease of various surgical steps. Both laser platforms created similar corneal incisions. Incision placement with respect to the limbus was more difficult with the LenSx, and I found the actual positions of the main and side port incisions to be more central in the cornea than expected. This created more striae and more difficulty removing subincisional cortex. The main incision created by both systems was easy to open using blunt dissection with a spatula, but it was more difficult to open the superior side port incision made by the Catalys.
I consistently noted smaller pupils in the LenSx cases despite excellent preoperative dilation, as opposed to rarely seeing this with the Catalys cases. I surmise that the laser induced pupillary miosis results from the higher energy of the LenSx laser.
As previously mentioned, the capsulotomies were all complete with the Catalys whereas there were some micro-adhesions from the LenSx despite using a PI with the SoftFit contact lens. Prior to hydrodissection, it is recommended that the surgeon gently rock the lens nucleus to release gas bubbles behind the lens. I found it easier to release the gas bubbles in the Catalys cases because more and bigger bubbles were produced by the Catalys grid fragmentation pattern than with the LenSx cylinder pattern. Hydrodissection therefore seemed to be easier to accomplish in the Catalys cases because of the greater amount of pneumodissection and my ability to more effectively release the gas bubbles. Also, as stated previously, the Catalys cases required significantly less phaco energy/time than the LenSx cases because of the capability of the Catalys to fragment the lens into a grid pattern.
Conclusion
My experience with the Catalys and LenSx devices has been positive. I believe both systems are helpful for cataract surgery, particularly in difficult cases. The learning curve of both machines is rapid, particularly for surgeons who have experience using femtosecond lasers for corneal refractive surgery, and I felt comfortable with each platform after just a few cases. I performed the laser cases in a preop area with plenty of space and found the workflow to be similar for the two platforms. However, the smaller footprint of the Lenx makes this device easier to place directly in the operating room where space is often limited. There are pros and cons to both systems, but I believe that the added safety of the Catalys is a distinct advantage. Nevertheless, if you are considering adopting femtosecond laser technology for cataract surgery, it is essential to thoroughly evaluate the different systems and if possible to get hands on experience with them. Both AMO and Alcon provided excellent service and support during my trial period.
Disclosure: Dr. Friedman is a consultant to OptiMedica.