BLOG: How my femto settings have evolved
One of the benefits of femtosecond laser-assisted cataract surgery is the ability to pre-soften the nucleus, thereby minimizing phaco energy and phaco time.
I was an early adopter of FLACS using the Catalys femtosecond laser (Johnson & Johnson Vision) and have performed more than 1,000 procedures with this laser to date. Surgeons have the ability to use this laser with its default settings or — if so inclined — to customize many of the settings and parameters. I’ll share with you the “then” and “now” of how my thinking on lens segmentation patterns and degree of softening has shifted.
First, it’s important to know that this laser gives users the option to segment the lens into quadrants, sextants or octants. One can also soften the lens in a grid pattern throughout the lens or in a smaller area within each of the four, six or eight segments. The cube size for the softening grid ranges from 100 µm to 2,000 µm. Finally, the width of the non-softened segmentation area can also be adjusted.
Then: Initially, I took full advantage of the ability to customize all of the above parameters according to lens density. I established preset patterns for grades 1, 2, 3 and 4 nuclei (Figures 1a and 1b). In refractive lens exchange cases for grade 2 dysfunctional lenses, for example, I would just segment the lens into four quadrants with no additional softening. For grade 4+ nuclei, I would use octants and the smallest cube size for the softening grid. This system generally worked very well. With time, I did experience a few cases of retained nuclear fragments with the smallest cube sizes. I also noticed that surgeons using peristaltic-only systems, which require full occlusion to build vacuum, were having some difficulty with the smaller cubes, too.
Now: Today I use the same pattern for most eyes across varying nuclear densities. My “femto prechop” approach is a quadrant segmentation with a micro-cruciate pattern at the distal ends of each quadrant (Figure 2). This has a number of advantages. It clearly demarcates the lens and makes it easy to chop centrally, while the distal cruciate pattern provides an ideal space to engage the peripheral nucleus in each quadrant with a Seidel chopper to rotate the lens with ease. The treatment time is fast, and my decision-making has been streamlined. The precise nucleofragmentation that the laser provides makes vertical chopping of soft nuclei easy, and the larger cube size provides plenty of surface area to build occlusion for those surgeons using a peristaltic-only phaco system. The slight increased incidence in retained lens fragments with small cubes has disappeared with the femto prechop technique.
The femto prechop setting is an elegant vertical chop technique that is effective for most lenses, and I will occasionally increase the softening pattern for brunescent lenses.
Disclosure: Waring reports he is a consultant for Johnson & Johnson Vision and a member of the Johnson & Johnson Vision optics advisory board.