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Lower energy surgery delivered with and without femtosecond laser

Less energy reduces risk of endothelial damage in dense cataract removal.

Issue: December 25, 2018

ByKendall E. Donaldson, MD, MS

BySumitra S. Khandelwal, MD

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Welcome to another edition of CEDARS/ASPENS Debates. CEDARS/ASPENS is a joint society of cornea, cataract and refractive surgery specialists, here to discuss some of the latest hot topics in ophthalmology.

Managing the dense cataract and the white cataract has long been a struggle for many surgeons. Recently, several new devices have become available to help tackle this problem. These include the femtosecond laser, for both creation of the capsulorrhexis and nuclear fragmentation, the miLOOP (IanTECH/Zeiss) for nuclear fragmentation and the Zepto device (Mynosys) for capsulotomy creation.

This month, Kendall E. Donaldson, MD, MS, and Sumitra Khandelwal, MD, discuss their preferred approaches.

We hope you enjoy the discussion.

Kenneth A. Beckman, MD, FACS
OSN CEDARS/ASPENS Debates Editor

Femtosecond laser-assisted lens pre-fragmentation an excellent tool for dense cataracts

Dense cataracts can pose challenges for even the best cataract surgeons. These cataracts are frequently accompanied by other ocular pathology including pseudoexfoliation syndrome, small pupils, weak zonules and capsule integrity alterations, which can make these cases high risk.

In all these cases, the femtosecond laser is an excellent tool to help facilitate nuclear fragmentation, as well as to ensure a perfect capsulotomy and potentially reduce manipulation of the lens material, thus reducing stress on the zonules during the case.

Less energy

Source: Kendall E. Donaldson, MD, MS

Many studies have validated the decreased use of phacoemulsification energy during cataract surgery when the femtosecond laser is used. This reduced energy is particularly beneficial in dense cataract cases that otherwise risk corneal endothelial damage because of longer phaco times at higher energy levels.

In a multicenter study published in the Journal of Refractive Surgery, Zaina Al-Mohtaseb, MD, and colleagues demonstrated a statistically significant decrease in cumulative dissipated energy and less endothelial cell loss in eyes with dense cataract pretreated with femtosecond laser. Fragmentation patterns and surgical techniques varied among cases, and no difference was found in results between use of either the Catalys (Johnson & Johnson Vision) or the LenSx (Alcon) laser platform. At Bascom Palmer Eye Institute, we achieved a 42% reduction in cumulative dissipated energy over traditional femtosecond surgery when pretreating LOC grades I, II and III cataracts using the LenSx and Catalys lasers. In fact, all the femtosecond laser platforms — Catalys, LenSx, Lensar (Lensar) and Victus (Bausch + Lomb) — have been found to reduce cumulative dissipated energy, which results in less traumatic surgery, ultimately preserving surrounding structures, such as the corneal endothelium.

In combination with chopping techniques, the femtosecond laser can provide pre-fragmented chopping planes to facilitate the process of lens fragmentation and removal, improving both safety and efficiency of cataract surgery. Each of the femtosecond lasers provides a variety of lens fragmentation patterns for the surgeon to customize according to personal preferences and lens density (Figure 1).

Capsulotomy and fragmentation

Patients with vulnerable endothelium, such as those with Fuchs’ dystrophy, can benefit from less energy being put into the eye, resulting in a more atraumatic case. In pseudoexfoliation, when material builds up on the anterior capsule and changes the integrity of the lens, making it more friable and less stable, using the laser for both the capsulotomy and the lens fragmentation can minimize nuclear manipulation and avoid stressing the zonules. These patients can have also small pupils, which can be managed by first placing a Malyugin ring (Microsurgical Technology) to keep the pupil stretched wide enough to complete the laser procedure. Pupils tend to constrict during pre-fragmentation due to the laser triggering the release of prostaglandins, but even so, pre-fragmentation can facilitate removal of the nuclear fragments.

Ultimately, any tool that can help us make surgery safer, easier and more efficient is a welcome addition to the cataract surgeon’s armamentarium.

• References:
• Abell RG, et al. J Cataract Refract Surg. 2014;doi:10.1016/j.jcrs.2014.05.031.
• Abell RG, et al. Ophthalmology. 2013;doi:10.1016/j.ophtha.2012.11.045.
• Al-Mohtaseb Z, et al. J Refract Surg. 2017;doi:10.3928/1081597X-20170731-01.
• Conrad-Hengerer I, et al. J Cataract Refract Surg. 2015;doi:10.1016/j.jcrs.2014.10.044.
• Conrad-Hengerer, et al. J Refract Surg. 2012;doi:10.3928/1081597X-20121116-02.
• Daya SM, et al. J Cataract Refract Surg. 2014;doi:10.1016/j.jcrs.2013.07.040.
• Fan W, et al. J Cataract Refract Surg. 2018;doi:10.1016/j.jcrs.2018.05.007.
• Scott WJ, et al. J Cataract Refract Surg. 2016;doi:10.1016/j.jcrs.2016.04.027.
• Yesilirmak N, et al. J Cataract Refract Surg. 2017;doi:10.1016/j.jcrs.2016.11.037.

• For more information:
• Kendall E. Donaldson, MD, MS, can be reached at Bascom Palmer Eye Institute, 8100 SW 10th St., Crossroads 3, Suite 3000, Plantation, FL 33324; email: kdonaldson@med.miami.edu.

Disclosure: Donaldson reports she is a consultant for Alcon, Johnson & Johnson and Bausch + Lomb.

Femtosecond laser-assisted lens pre-fragmentation not needed for dense lenses

Dense lenses can be challenging, and any tool to assist the surgeon is appreciated. The femtosecond laser has added to our ways to tackle these cases; however, exciting new tools are available that may not require an expensive laser. This is especially important considering that sometimes the most complex cases are not ones in which the patient or surgeon has the resources to support the use of the laser.

Dense lenses

For cases in which the lens is dense, a new tool called the miLOOP is now available at a disposable price point that any surgery can afford. The device uses a thin filament wire that wraps around the nucleus and cleaves it into segments (Figure 2). The wire can cut in a way that even the dense settings on the phaco machines cannot. Even some femtosecond platforms can falter in truly cracking these dark red or black lenses, but the miLOOP can. Furthermore, in my experience, I have found that the femtosecond laser can fragment these dense lenses but not always deeply enough to divide the thick epinuclear plate. The miLOOP, on the other hand, excels at cutting deeply, so there is no plate.

Zonulopathy

Source: Sumitra S. Khandelwal, MD

The outside-to-inside cutting and energy-free nuclear disassembly of the miLOOP minimizes stress on the capsule and is much gentler on the zonules, as demonstrated on Miyake views. Proper chopping techniques and two-handed rotation tend to prevent excessive zonule loss as well.

In addition, the device can be used in small pupil cases. Pupillary expansion can be performed first before insertion of the device, while the femtosecond cannot be used in small pupil cases unless the surgeon chooses to dilate with a device and return back to the laser room. In addition, the miLOOP can be used when the view to the lens is poor, such as corneal scarring or Fuchs’ dystrophy (Figure 3). This would not be possible if the laser is not able to visualize the anterior capsule or lens despite its OCT capabilities.

Lastly, there are times when zonular loss is caused iatrogenically when a less experienced surgeon encounters a tough cortex. The act of cutting the lens into fragments with the miLOOP removes much cortex as well, which can sometimes be more challenging in femtosecond cases.

White cataract

In white cataracts, using the femtosecond laser to create a quick capsulorrhexis without anterior capsule run-out is helpful. Alternatively, the Zepto pulse capsulotomy device can be used to do the same. The Zepto employs low-energy pulses to create a precise capsulotomy, independent of pupil size, corneal clarity or lens density. Inserted through a clear corneal incision, the device uses a gentle suction to create a uniform capsular contact. Electrical nanopulses are delivered to a nitinol ring to create the capsulotomy with no cautery or burning of tissue.

In summary femtosecond has excellent applications in complex cataract surgery, and our center utilizes it when possible. However, with new exciting tools to tackle these dense cataracts, such as miLOOP and Zepto, those who do not have access to a femtosecond laser or the resources to use it can rest assured that they can still achieve excellent outcomes.

• For more information:
• Sumitra S. Khandelwal, MD, can be reached at Baylor College of Medicine, 1977 Butler Blvd., 2nd Floor, Houston, TX 77030; email: sumitra.khandelwal@bcm.edu.

Disclosure: Khandelwal reports she is consultant for IanTECH and Alcon.