Laser cataract surgery favored over phaco for reducing ultrasonic energy use

Take-home message: The Laser Cataract Consortium, comprising five experienced laser cataract surgeons, undertook a study incorporating rigorous collection of data from 7,200 eyes undergoing cataract surgery.

By Cheryl Guttman Krader; Reviewed by Jonathan D. Solomon, MD

Bowie, MD-Femtosecond laser-assisted cataract surgery is at least as safe and efficient as standard phacoemulsification, but has a clear benefit for significantly reducing ultrasonic energy use, said Jonathan D. Solomon, MD.

Such are the results from a large, prospective multicenter study including more than 7,200 eyes. The study, undertaken by the Laser Cataract Consortium, was conducted at four clinical sites and involved five surgeons (Dr. Solomon, Neel Desai, MD, Paul Kang, MD, Robert Weinstock, MD, and William Wiley, MD) who were experienced in laser cataract surgery, each already having performed more than 100 cases.

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All four cataract surgery femtosecond laser platforms available in the United States (Catalys, Abbott Medical Optics; LENSAR Laser System, LENSAR; LenSx, Alcon Laboratories; Victus, Bausch + Lomb) were represented across the different centers, as were three different phacoemulsification systems (Infiniti Vision System with OZil, Alcon; Whitestar Signature with Ellips FX, Abbott Medical Optics; Stellaris, Bausch + Lomb).

In total, the non-randomized study included 2,231 eyes operated on with laser cataract surgery and 5,000 eyes that underwent traditional phacoemulsification using the surgeon’s preferred method.

Recorded data included patient-reported pain with the laser procedure, phacometrics (total ultrasound energy or time and infusion volume), and complications, as well as surgeon-graded ease of docking, subconjunctival hemorrhage/chemosis, capsulotomy completeness, wound opening ease, and incision integrity with laser cataract surgery. Standardized definitions and scales were used for data collection.

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“Previous studies have evaluated the ease, surgical efficiency, safety, and impact on phacodynamics and fluidics of laser cataract surgery,” said Dr. Solomon, director of refractive/cataract surgery, Solomon Eye Physicians and Surgeons, and research director, Bowie Vision Institute, Bowie, MD. “While those studies include several very large series, they were all from a single center using only a single laser system.”

Significance of findings

The consortium study is prospective, uses a standardized data collection form, comprises the largest population of patients to date, represents a full range of cataract densities, and is the first to include multiple surgeons evaluating multiple platforms using a standardized approach to data collection, he noted.

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“Our findings should dispel concerns that have been raised about anterior capsular tears and capsular rents using the laser for capsulotomy,” Dr. Solomon said. “However, perhaps the main take-home message is that laser cataract surgery is a much better way to remove denser cataracts because it reduces ultrasound energy use, which has potential implications for corneal safety and visual recovery.”

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Patients were eligible for the study if they had no contraindications to laser cataract surgery and were willing to pay customary out-of-pocket costs. Patients with small pupils, intraoperative floppy iris syndrome, or zonulopathy were not excluded, but those complexities were to be recorded when they were encountered.

Mean patient age was similar in the laser cataract surgery and standard phaco groups (~70 years). The laser was used by all surgeons for capsulotomy and lens fragmentation and for clear cornea incisions in about 30% of cases.

Data analyses

Analyses of laser cataract surgery data showed average suction time was about 3 minutes, and there was a 2.7% incidence of suction break. Mean capsulotomy size was 5.55 mm with a standard deviation of 0.25 mm.

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“There has been information suggesting that the risk of radial tears with laser capsulotomy is increased if the diameter is <5 mm,” Dr. Solomon said. “In our series, the overwhelming majority of capsulotomies were larger than 5 mm.”

A complete capsulotomy with 360° anterior capsular lysis was achieved with the laser in 96.9% of eyes.

“These data speak to the fact that all of the surgeons in our group were well beyond their learning curve with the laser and had the expertise to check such factors as head position and aberrations during laser delivery that could interfere with complete capsular lysis,” Dr. Solomon said.

Results from ratings of the docking experience in the laser cataract surgery cohort using a scale of 0 (easy globe fixation, corneal centration, and/or applanation) to 4 (unable to fixate the globe, maintain centration or applanation) showed it was relatively easy with a mean score of 0.96. Mean docking time was almost 3 minutes and the mean docking time was less than 2.5 minutes.

Next: Engery, infusion volume

Subconjunctival hemorrhage/chemosis had a mean grade of 2 on a scale ranging from 0 (minimum) to 4 (maximum). Patients reported minimal pain during the laser procedure, with an average score of 1.22 using a scale of 0 (no pain) to 10 (the most uncomfortable you have ever been).

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“There were a few outliers, but the individual scores were skewed to the lower end of the scale, and the patient’s perception of the laser procedure was that it was very gentle overall,” Dr. Solomon said.

Ease of incision opening for both primary and arcuate incisions was rated with an average score of 2, corresponding to requiring moderate effort with blunt dissection.

Energy, infusion volume

Measurements of phacoemulsification energy showed an overall reduction of 42% with laser cataract surgery. When eyes were stratified by nuclear density into five groups (grade 1 to 4+), the benefit of the laser was statistically significant in all groups.

However, the percentage reduction in phacometric energy dispersion in eyes with Grades 3, 4, and 4+ cataracts (42% to 53%) was greater than in the lower density groups (34% to 36%).

Infusion volume data were collected as a surrogate for determining how use of the laser impacted intraoperative time for the phacoemulsification portion of the procedure. Average infusion volume was nearly identical for the laser cataract surgery and standard phacoemulsification groups (198 versus 195 cc), Dr. Solomon said.

Data on complications showed there was one case of vitreous loss in both the laser cataract surgery and standard phacoemulsification groups, single cases of a capsular rent in both groups, and a single radial tear after laser capsulotomy.

Jonathan D. Solomon, MD

E: jdsolomon@hotmail.com

This article was adapted from Dr. Solomon’s presentation during the 2015 meeting of the American Society of Cataract and Refractive Surgery. Dr. Solomon is a consultant to Abbott Medical Optics and LENSAR.