FEMTO FACTOR

Now that you have it … how do you use it?

The femtosecond laser doesn’t come with an instruction manual for surgery.

By Scott LaBorwit, MD

I couldn’t believe my new gas grill came in a box that could barely fit a pair of shoes. Inside were more parts and different size screws, nuts and bolts than one could imagine. Of course, the first thing I did after finding the instruction manual was put it aside — I wasn’t going to let it slow me down. I always joke with my kids that instruction manuals are optional. But sizing up an Ikea shelf is very different from calculating near distance in the operating room. In fact, many times over the last three years I’ve thought how helpful it would be to have a how-to in the drawer next to my femtosecond laser to tell me everything I need to know about using it in cataract surgery.

The laser training I received prior to my first LACS case was excellent. It included a site visit to see it in action, an online tutorial and a one-on-one personal training session with a trainer from the laser company. By the time my first case arrived I was very comfortable with the technology — but I knew the imaging and laser application possibilities were endless, and my surgical technique has evolved and consequently improved multi-fold. As more surgeons adopt the technology, I am sure they are discovering their own new applications.

But improvement and mastery are easier to achieve with a plan. Here are steps I take to ensure my technique continues to evolve.

CAST YOUR NET WIDE

A first step is to establish how to obtain and filter relevant information. Peer-review journals and ophthalmic meetings are excellent sources, of course, but do not discount valuable tips in more informal settings. Casual conversations with other professionals, I’ve found, often provide new information. The best pearl I gained this year came from a laser-training specialist in my OR; although he was visiting me for another reason, he mentioned a new way to create a triplanar primary incision with creative settings used by another surgeon who had the same system as me. The technique cut my capsulorhexis time in half while delivering equal results.

While having dinner at last year’s Academy meeting, I learned a different pattern to cut posterior capsules during a YAG capsulotomy, which allowed the capsule to open quickly using fewer laser applications and resulting in fewer frequent floaters. These were brief conversations that have had major impacts on my current practice.

Keep in mind when sharing ideas with other surgeons, though, that what works for some may not work for others. And some surgeons promote techniques they have only used in a few cases, so they aren’t always tried and true.

BE AN EXPLORER

When I’m driving to an unfamiliar destination I’m never really lost, I’m just exploring (if my wife isn’t in the car). I feel the same way about my journey with LACS. I am always looking for new information and ways to improve, but that doesn’t always mean looking to others.

Surgeons need to be flexible about this process. Take those well-honed, instinctive skills and tools you use in surgery and change them up. You may try changing laser settings over time to better understand their impact — although to do this you need to understand what each setting means, such as spot size, skip layers and energy power. I found increasing my spot energy slightly allowed me to increase my skip layers for nuclear fragmentation. Over all, I used less energy and less treatment time without compromising fragmentation.

Other changes to consider involve the geometry of the laser application. For this, the corneal primary incisions are affected by width size, length and angles. Other geometric considerations include the patterns and size of laser cuts into the lens. I came full circle on primary corneal incisions: I began triplanar, then went biplanar and now am back to triplanar, and very happy with the results. The newer triplanar incision has a steeper initial angle, a longer track with a lower spot energy and seals well.

While investigating the diameter of the nuclear core cylinders, I would change the laser spot separation, on some days, every 10 cases until I found a sweet spot. It took me years to figure out the most comfortable cylinder diameter to cut the core of my lens. It was 3.0 mm in diameter, then 6.0 mm in diameter and now I use 4.7-mm diameter with five cylinders for most of my cases.

My favorite femto discovery was recognizing that its imaging component is actually more powerful than its laser. This lets me guide the laser, via the computer, to precisely and accurately treat the eye. This component has had a great impact on my outcomes. For example, the imaging will allow my astigmatic keratotomies to be at the 9-mm optic zone from the visual axis, 85% depth of this patient’s cornea based on OCT imaging, and the cord length is cut to a precise degree. Even the axis is found on the supine patient using preoperative imaging to mark blood vessels in the sitting patient. I cannot reproduce this manually.

Understand that not all modifications will work out. When I increased my spot energy for the capsulotomy, there was more energy near the pupil border. I felt the pupil would come down more often during the case and quickly changed it back.

YOU CAN’T STAND STILL

Femtosecond technology is evolving so quickly that it would be hard to keep a manual up-to-date. It is not enough to integrate LACS and stop there — you must be able to ride the wave as the technology changes, bringing new benefits to your patients. OM

Scott LaBorwit, MD, is a principal at Select Eye Care, with locations in Towson and Elkridge, Md., and is an assistant professor, part-time faculty, at Wilmer Eye Clinic of Johns Hopkins Hospital, Baltimore. His e-mail is Sel104@me.com. Disclosures: Dr. LaBorwit is a consultant to and speaker for Alcon.