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A little microburst goes a long way
Microburst phaco techniques in conjunction with femtosecond laser-assisted cataract surgery can result in faster surgery with less ultrasound power.
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Since introducing femtosecond laser-assisted cataract surgery, or FLACS, to my weekly cataract armamentarium 4 years ago, I have gone through many procedural changes to optimize patient visual outcomes in terms of faster visual recovery time, reduced inflammation and reduced corneal edema.
As premium cataract surgeons, we should always seek ways to reduce the cascade of events that cause surgical stress during cataract surgery, a process that we know begins before incision creation followed by the well-known arachidonic cascade of inflammation and finally ends with postoperative corneal edema. The ultimate goal in cataract surgery is to perform the procedure with minimal disruption to other tissues, with minimal to no heat/thermal damage, and reduced phacoemulsification time and reduced volume of irrigation and aspiration fluid. Preoperative cataract density based on the LOCS III classification system has a direct impact on all of these variables, and techniques for gentler cataract surgery are critical to get to the best visual outcome. Below I will describe various techniques and ultimately the newer and ever more popular microburst phacoemulsification technique used in conjunction with FLACS to get these immediate results.
Techniques for gentler surgery
It is a commonly known fact among premium cataract surgeons that chopping techniques utilize less ultrasound energy consumption than divide-and-conquer techniques, dispersive viscoelastics create more heat production than cohesive forms, and less manipulation of the incision, less epithelial trauma and less endothelial loss all result in smoother surgery. Foreign substances such as povidone- iodine, trypan blue and intracameral antibiotics can all affect surgical inflammation postoperatively. Intraoperative difficulties such as a denser nucleus, broken posterior capsule, retained nucleus/cortex, iris turbulence/trauma, floppy iris, zonular damage and/or intraoperative miosis can all contribute to a less smooth outcome. The good news is that FLACS can reduce phaco energy delivered to the eye by fragmenting and softening the nucleus, and delivering ultrasound with smaller pulses of steady energy (microburst) after fragmentation further minimizes tissue trauma. Not all femtosecond laser systems are equal in their capabilities despite similar FDA labeling for lens fragmentation. An example is the advanced Scheimpflug imaging utilized by the Lensar femtosecond laser, which can optimize fragmentation patterns based on its ability to grade cataracts, no different than LOCS III grading in terms of nuclear density patterns.
Any substantial reduction in phaco energy is highly beneficial in terms of visual recovery and outcomes. There are certain phaco systems that have zero phaco potential after FLACS, but minimizing phaco energy is the primary goal. It is equally important to avoid running huge volumes of fluid through the eye in an attempt to minimize phaco energy. Use of FDA-approved intracameral solutions to maintain pupillary dilation such as Omidria (phenylephrine 1% and ketorolac 0.3%, Omeros) can also be beneficial in cases in which iris turbulence/floppiness is expected in patients taking tamsulosin or other -osin-like prostate medications.
Personal experience
My personal approach to FLACS-treated lens removal involves efficient high vacuum aspiration, dual-linear control of power and vacuum, and minimal to no post-occlusion surge with use of Stellaris (Bausch + Lomb) 1.8 mm to 2 mm microincision phacoemulsification. The Stellaris microburst setting is more energy efficient with 26% to 28% ultrasound power, 1% to 75% duty cycle (waveforms per cycle), 8 millisecond burst duration and 60% waveform depth. Cortex removal with the CapsuleGuard IA (Bausch + Lomb) in a tangential circumferential pattern is also highly efficient with minimal surrounding tissue trauma. In a recent retrospective evaluation of 600 FLACS cases with the Lensar laser and the Stellaris microburst technique described above, the average effective phaco time was 1.1 seconds at an average ultrasound power of 11.2% compared with an average effective phaco time of 4.6 seconds and 12.5% average power with Stellaris microburst alone without FLACS. The impact of FLACS on reduced inflammation and ultrasound energy levels has already been well established and published prior to my own retrospective evaluation.
Ultimately, a reduction in ultrasound energy, especially in more complex cases such as shallow anterior chambers, pseudoexfoliation and/or Fuchs’ corneal dystrophy, should lead to a reduction in corneal edema, endothelial loss and postoperative inflammation. And utilizing modern-day energy-efficient microburst phacoemulsification techniques in conjunction with FLACS will go a long way in preserving and enhancing visual outcomes for the premium cataract surgeon.
- References:
- Abell RG, et al. J Cataract Refract Surg. 2013;doi:10.1016/j.jcrs.2013.06.009.
- Conrad-Hengerer I, et al. J Cataract Refract Surg. 2012;doi:10.1016/j.jcrs.2012.07.023.
- Mayer WJ, et al. Am J Ophthalmol. 2013;doi:10.1016/j.ajo.2013.09.017.
- Schultz T, et al. J Refract Surg. 2013;doi:10.3928/1081597X-20131021-03.
- Schultz T, et al. J Refract Surg. 2015;doi:10.3928/1081597X-20150122-01.
- For more information:
- Mitchell A. Jackson, MD, can be reached at Jacksoneye, 300 N. Milwaukee Ave., Suite L, Lake Villa, IL 60046; email: mjlaserdoc@msn.com.
Disclosure: Jackson reports he is a consultant for Bausch + Lomb, Omeros and Lensar.