Eliminating ultrasound during lens removal

Take Home

With femtosecond laser lens pretreatment and optimization of the surgical approach, removal of even dense cataracts (LOCS III grade 4) can now be completed without any ultrasound in nearly all cases.

Dr. Schultz

By Cheryl Guttman Krader; Reviewd by Tim Schultz, MD

Bochum, Germany-Nucleus pretreatment with a femtosecond laser is bringing cataract surgery close to the goal of achieving lens removal without ultrasound, said Tim Schultz, MD.

Dr. Schultz, resident, Ruhr-University Eye Hospital, Bochum, Germany, presented findings from a prospective study of 2,400 consecutive eyes that underwent femtosecond laser-assisted cataract surgery (LCS) between December, 2011, and this past October.

All of the procedures were performed by Burkhard Dick, MD, PhD-professor and chairman, department of ophthalmology, Ruhr-University of Bochum, Germany-using the same femtosecond laser platform (Catalys Precision Laser System, Abbott Medical Optics) and the same phacoemulsification unit (Stellaris Vision Enhancement System, Bausch + Lomb). However, various refinements in technique and other instrumentation were introduced over time.

Examining the study

Data on effective phaco time (EPT) were analyzed as a measure of ultrasound energy usage from the first 650 LCS cases-which represented the learning curve cohort-the next 1,000 LCS cases, and the last 400 cases. Outcomes for the first two cohorts were compared with equally sized control groups of eyes operated on with standard manual techniques.

Focusing on eyes with cataract grades 2 to 4 (LOCS III classification), the results showed laser pretreatment of the lens significantly reduced ultrasound energy usage across all grades of cataract.

Data from the three LCS cohorts showed that ongoing optimization of the surgical approach successfully resulted in progressive reductions of ultrasound usage.

Among the last 400 eyes in the LCS series (cases 2001 to 2400), ultrasound was required to complete lens removal in only 3 eyes, all of which had more advanced cataracts (LOCS III NO score = 4).

“The laser system and settings used allow a normal hydrodissection,” Dr. Schultz said. “Furthermore, after full fragmentation, the lens can be aspirated with minimal movement of the the phaco tip in the middle of the anterior chamber in most of the cases.”

All of the eyes in the series had lens nuclear and cortical density graded at the slit-lamp by an independent European Vision Clinical Research Institute-certified physician. Eligible eyes had a LOCS III NO score of 1 to 4 as well as a pupil size >6 mm.

Patients also had to be at least 22 years of age. The LCS and control groups were matched for LOCS III grades.

In the learning curve LCS cohort (mean LOCS III score = 3.2), mean EPT values for eyes with grades 2 to 4 cataract ranged from 0.01 seconds to 0.23 seconds, whereas mean EPT values in the control group ranged from 1.52 seconds to 3.30 seconds.

In the LCS group, 70% of eyes underwent cataract surgery without the need for any ultrasound, including 90% of those with grade 2 cataracts and about two-thirds of those with grade 3 or 4 cataracts.

Surgical optimizations introduced after the first 650 LCS cases included changes in the phaco machine settings and the phaco tip, as well as removal of the anterior chamber maintainer.

In addition, changes were made to the femtosecond laser lens pretreatment that included a decrease in the grid size and changes in the repetition rate for the cuts made in the middle of the nucleus.

Diving deeper

Data from the next 1,000 LCS cases showed that 95% of eyes could be operated on without ultrasound.

With eyes divided by cataract grade, 100% of eyes with grade 2 cataracts, 98% of those with grade 3 cataracts and 87% of those with grade 4 cataracts had zero ultrasound surgery. Mean EPT values for the LCS cases ranged from 0 in eyes with grade 2 cataracts to 0.08 seconds for those with grade 4 cataracts.

In the control groups, mean EPT values ranged from 1.52 to 4.06 seconds.

Further optimizations were subsequently introduced, including use of a new aspiration tip (MST). For the last 400 eyes in the study, > 99% of procedures were performed without ultrasound.

Tim Schultz, MD

E: dr.tim.shultz@googlemail.com; tim.schultz@kk.bochum.de

Dr. Schultz has no relevant financial disclosures. Dr. Burkhard was a consultant to Optimedica.

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