July 2018

CATARACT

Research highlight
Optimizing femto fragmentation patterns based on lens density lowers phaco time


by Liz Hillman EyeWorld Senior Staff Writer




A grid fragmentation pattern was shown to result in lower effective phacoemulsification time, compared to a pie fragmentation pattern, except in cases where the lens density was more than 12%.
Source: Mehdi Shajari, MD

Study finds lower effective phaco time with pie fragmentation pattern for denser lenses

The femtosecond laser has shown its ability to create a centered, perfectly round, reproducible capsulotomy. It also has the ability to make corneal, arcuate, and limbal relaxing incisions and perform nuclear fragmentation.
Several studies have shown femtosecond laser-assisted cataract surgery (FLACS) to be as safe and effective as conventional phacoemulsification cataract surgery, but little difference is seen in the visual or refractive outcomes.1 In terms of complications, intraoperative complications between FLACS and conventional cataract surgery have been shown to be similar, while postoperative complications in one study were lower in the traditional phaco group.2
A review published in the Cochrane Database of Systematic Reviews in 2016, which included 16 randomized controlled trials that compared FLACS with traditional cataract surgery, “could not determine the equivalence or superiority of laser-assisted cataract surgery compared to standard manual phacoemulsification.”3
Mehdi Shajari, MD, Department of Ophthalmology, Goethe University Frankfurt, Germany, and coinvestigators decided to dig deeper as to why this might be, surprised at the lack of a significant difference.
One of the points Dr. Shajari, along with principal investigator Thomas Kohnen, MD, PhD, chairman, Department of Ophthalmology, Goethe University Frankfurt, and coinvestigators evaluated in a study published in the Journal of Cataract & Refractive Surgery was fragmentation patterns and their effect on effective phacoemulsification time (EPT).4 Previous research had shown that FLACS could reduce ultrasound energy delivered to the eye with the potential to then reduce occurrence of corneal edema and endothelial cell loss.5
In a retrospective case series of 150 eyes, Shajari et al. compared a femtosecond laser pie fragmentation pattern (75 eyes) to a grid fragmentation pattern (75 eyes). The average EPT was higher in the pie pattern compared to the grid pattern (6.63 ± 5.41 seconds compared to 4.26 ± 6.99 seconds), and the number of eyes that required no ultrasound energy to be used in the case was higher with the grid pattern. Further analysis showed, however, that lens density was a factor. Cataracts with a lens density of more than 12% (nine eyes in each group) had a lower EPT when the pie nuclear fragmentation pattern was used.
Dr. Shajari said he thinks the lower EPT is significant enough to have a positive effect. As stated by Dr. Shajari and coauthors in the paper, lower EPT can lead to less corneal edema and endothelial cell loss. As such, Dr. Shajari thinks choosing a fragmentation pattern based on lens density is something that could be adopted by those using femto technology today.
“The research is at a level where this basic differentiation should be done. For general division in the very dense cataract and moderate or low cataract levels, [optimized lens fragmentation] is something we can do,” Dr. Shajari said, noting that further research should be done to refine pattern selection.
Dr. Shajari thinks the lower EPT with FLACS is especially useful in specific cases.
“When you have a patient with endothelial dystrophy and you know you shouldn’t use too much ultrasound power because this will reduce the cell count and lead to further side effects … when we know a way to decrease the ultrasound energy that we are giving to the eye, I think it makes a lot of sense for them. This would be for me a clear reason to shift from conventional cataract surgery to femto cataract surgery,” he said.
Lowering ultrasound energy delivered to the eye, Dr. Shajari said, could lead to less inflammation and a lower rate of cystoid macular edema.
Overall, Shajari et al. wrote, “more studies that assess the correlation between different fragmentation patterns and their effect on measurement outcomes such as EPT and cumulative dissipated energy are necessary.”
As a final point, Dr. Shajari mentioned that conventional phacoemulsification cataract surgery has had decades to improve, while FLACS is still in its relative infancy. Contributing to the “evolution of femto phaco” is something Dr. Shajari hopes more physicians will join in.
“It would be best if colleagues start to think about ways to not just use the technology as given but how we can improve the processes,” he said. “We should not wait until a company is coming out with a new laser, but [think of] how we as physicians can optimize what is given. Then I think we will be in a situation where we can compare or see the benefits of the technology because I think there is a lot still to it.”

References

1. Chen H, et al. Visual and refractive outcomes of laser cataract surgery. Curr Opin Ophthalmol. 2014;25:49–53.
2. Manning S, et al. Femtosecond laser-assisted cataract surgery versus standard phacoemulsification cataract surgery: Study from the European Registry of Quality Outcomes for Cataract and Refractive Surgery. J Cataract Refract Surg. 2016;42:1779–1790.
3. Day AC, et al. Laser-assisted cataract surgery versus standard ultrasound phacoemulsification cataract surgery. Cochrane Database Syst Rev. 2016;7:CD010735.
4. Shajari M, et al. Comparison of 2 laser fragmentation patterns used in femtosecond laser-assisted cataract surgery. J Cataract Refract Surg. 2017;43:1571–1574.
5. Hida WT, et al. Outcomes study between femtosecond laser-assisted cataract surgery and conventional phacoemulsification surgery using an active fluidics system. Clin Ophthalmol. 2017;11:1735–1739.

Editors’ note: Dr. Shajari has financial interests with Oculus (Wetzlar, Germany), Oertli Instrumente AG (Berneck, Switzerland), and Santen Pharmaceutical (Osaka, Japan).

Contact information

Shajari
: gms400@gmail.com

Optimizing femto fragmentation patterns based on lens density lowers phaco time Optimizing femto fragmentation patterns based on lens density lowers phaco time
Ophthalmology News - EyeWorld Magazine
283 110
220 216
,
2018-06-25T14:45:46Z
True, 7