August 01, 2013
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Femtosecond laser pretreatment cuts effective phaco time significantly

Lower phacoemulsification energy minimized endothelial cell loss, and improved capsulotomy design optimized visual and refractive outcomes.

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Femtosecond laser pretreatment significantly reduced effective phacoemulsification time in eyes undergoing cataract surgery, according to a study.

Perspective from Mark Packer, MD

Laser-assisted lens fragmentation resulted in zero effective phacoemulsification time (EPT) in almost one-third of eyes that underwent the procedure, the study authors said.

“The most significant finding from the study was that 30% of patients had zero effective phacoemulsification time. In our current series, this number has increased to around 80% zero EPT. Overall, there was an almost 85% reduction in EPT between manual cataract surgery and laser cataract surgery,” Brendan J. Vote, FRANZCO, the corresponding author, said in an email interview.

“Aside from the reduction in EPT, we were happy to report that all cases had a complete capsulotomy, and visual and refractive outcomes were improved in the laser group,” he said.

Brendan J. Vote, FRANZCO

Brendan J. Vote

Robin G. Abell, MBBS, and Nathan M. Kerr, MBChB, collaborated with Vote. The study was published in Ophthalmology.

Patients and methods

The prospective study included 150 eyes that underwent femtosecond laser pretreatment and phacoemulsification. A control group comprised 51 eyes that underwent conventional phacoemulsification.

Mean patient age was 72.8 years in the study group and 71.8 years in the control group.

The Pentacam Scheimpflug camera with the Pentacam Nuclear Staging System (Oculus) was used to measure cataract grade on a scale of 0 to 5. Mean cataract grade was 2.59 in the study group and 2.52 in the control group, with no statistically significant differences between the groups.

Pentacam Nuclear Staging grading correlated strongly with the Lens Opacities Classification System III, Vote said.

Laser pretreatment was performed with the Catalys femtosecond laser system (OptiMedica).

Subgroups of patients underwent lens fragmentation in different segmentation and softening grid patterns with the lens divided into equal quadrants. The effect of phacoemulsification tip size (20 gauge vs. 21 gauge) was also analyzed.

Full clinical assessment and pachymetry were performed 1 day after surgery. Full clinical assessment, objective autorefraction, corneal topography and specular microscopy were performed at 3 weeks.

Effective phacoemulsification time

Study results showed that mean EPT was 83.64% lower in the study group than in the control group (P < .0001). The reduction was significant across all grades of cataract (P < .01).

EPT was zero in 45 eyes in the study group (30%) and no eyes in the control group (P < .0001).

Data showed a strong relationship between cataract grade and EPT (P < .0001).

EPT was less than 4 seconds with cataract grades 1 to 3 on the Pentacam Nuclear Staging scale and more than 4 seconds but generally less than 8 seconds with grade 4 and 5 cataracts. EPT was less than 4 seconds in 80% of cases in the study group.

Improved lens fragmentation algorithms reduced EPT by 28.6%, and use of the 20-gauge phacoemulsification tip further reduced EPT by 72.8% (P < .0001).

“When optimization of grid patterns was coupled with a 20-gauge phacoemulsification tip, our total reduction in EPT between the optimized laser cases and the manual control group was over 96%,” Vote said.

Endothelial cell loss and refraction

Endothelial cell loss was 36.1% lower in the study group than in the control group; the between-group difference was statistically significant (P = .022).

“Our study did not directly measure the methods by which a reduced phaco time reduces endothelial cell loss,” Vote said. “However, with the average phacoemulsification time reduced by almost 85% in the laser group, it is possible that the decreased amount of ultrasound energy used results in less corneal endothelial cell damage.”

There was no significant difference in mean postoperative autorefraction at 4 weeks (–0.84 D in the study group and –0.75 D in the control group) or mean absolute error. However, the authors’ recent American Society of Cataract and Refractive Surgery presentation highlighted that with larger numbers in their ongoing studies, mean absolute error ±1 D was improved to 96.8% in the laser group from 92% in the control group (P < .03). – by Matt Hasson

Reference:
Abell RG, et al. Ophthalmology. 2013;doi:
10.1016/j.ophtha.2012.11.045.
For more information:
Brendan J. Vote, FRANZCO, can be reached at Launceston Eye Institute, 36 Thistle Street West, Launceston, Australia 7250; email: eye.vote@me.com.
Disclosure: Neither Vote nor his fellow authors have any relevant financial disclosures.