Laser refractive lens surgery: Is it safe or isn’t it safe?

TAKE HOME:

Surgeons with experience using the femtosecond laser for refractive lens surgery discuss the safety benefits and challenges accompanying its use.

Dr. Maloney

By Cheryl Guttman Krader; Reviewed by Michael Lawless, MD, and Robert K. Maloney, MD

Accumulating data published in the peer-reviewed literature demonstrate that laser refractive lens surgery (LRLS) performed with a femtosecond laser offers certain safety advantages compared with manual surgery.

However, surgeons who undertake the laser-assisted procedure must be aware that unique safety issues accompany it, making appropriate patient selection critical.

“If we can remove unpredictable events, perform specific tasks with greater precision, decrease the chance of damage to collateral structures, introduce previously impossible maneuvers, and do all of that reproducibly, then we have a safer operation,” said Michael Lawless, MD, medical director, Vision Eye Institute, Chatswood, NSW, Australia, and clinical senior lecturer, Department of Ophthalmology, Sydney University Medical School.

“There is now a body of evidence in the peer-reviewed literature from which we can say that LRLS has been shown to be or is likely to be safer than a manual procedure,” he said.

At the time of his presentation, Dr. Lawless identified 74 papers reporting on outcomes of LRLS, of which 4 were randomized controlled trials, 12 were controlled longitudinal studies, 7 were considered to provide grade A or B evidence, and 7 would be given a grade C evidence rating.

Summarizing the findings, Dr. Lawless said that use of the laser creates more precise and more predictable corneal incisions. It can also be stated unequivocally that the capsulotomy created with the laser is more precise relative to a manual capsulorhexis and has equivalent if not better strength.

Dr. Lawless noted that there have been some studies suggesting that the laser-created capsulotomy is inferior in terms of smoothness of the cut surface.

However, that research was conducted with older laser technology and higher energies than are currently used. Results of a recent study [Mastropasqua L, et al. J Cataract Refract Surg. 2013;39:1581-1586] showed that irregularity of the cut surface was similar comparing manual and laser capsulotomies when the latter was performed with a low energy setting of just 7 microJ.

“We are now in a low energy environment with the use of our lasers, and many systems are even operating below 7 microJ,” Dr. Lawless said, adding that he expects the quality of the capsulotomy edge created with the laser will soon be as good or exceed that of the manual capsulorhexis for most systems. How edge quality relates to capsule integrity is still to be determined.

Multiple studies investigating the effect of laser-assisted surgery on ultrasound energy usage show effective phaco time is reduced 40% to 90% relative to a manual procedure. Moreover, the reduction in ultrasound energy has been directly related to a benefit for minimizing endothelial cell loss, according to several studies.

In addition, two studies and various case reports show macular thickening is reduced by use of the laser, and there are case series describing use of the laser to facilitate surgery in difficult cases, including eyes with white cataract, phacomorphic glaucoma, a corneal graft, and those requiring mechanical pupil enlargement.

Focusing on surgical complications, Dr. Lawless cited a paper from his practice group that analyzed outcomes in a prospective cohort of 1,500 eyes consecutive eyes [Roberts TV, et al. Ophthalmology. 2013;120:227-233]. Using published data for manual surgery to benchmark the results, Dr. Lawless observed that the rates of posterior capsular tears, including events with and without vitreous loss, and of anterior capsular tears were lower than the best published historical results.

The rate of posterior capsule complications using the laser (0.08% or 0.23% for cases with vitreous loss) were also far better than the 2% rate reported in an analysis of data from 600,000 eyes in the Swedish National Cataract Register, Dr. Lawless said.

“In my personal series of 981 eyes, I have a 0.1% anterior capsular tear rate and a 0% rate of posterior capsule tears. I could never achieve those outcomes with manual surgery,” he added.

Counterpoint: Laser procedure not safer than manual approach

Robert K. Maloney, MD, first established his preference is for using the laser. He said that he has been performing LRLS routinely for 2 years and has experience with three of the four systems available in the United States.

However, he noted that he has encountered complications using all three systems and emphasized that the laser introduces different safety issues. He cited the paper from Dr. Lawless to highlight the learning curve for the laser-assisted procedure.

In addition, using surgical videos, Dr. Maloney reviewed the potential for anterior capsule tears using the laser along with the challenges of cortex removal and operating on eyes with small pupils.

“I try to avoid the femtosecond laser procedure in patients with small pupils because I think it makes a challenging situation even more difficult,” said Dr. Maloney, director, Maloney Vision Institute, and clinical professor of ophthalmology, UCLA Jules Stein Eye Institute, Los Angeles. “In addition, surgeons should know that cortical removal is more difficult in 100% of eyes in procedures done with the laser, and that is an issue rarely spoken about.”

He explained that in the laser-assisted procedure, the hydrodissection wave separates cortex from the epinucleus, not from the capsule, and after the laser-created capsulotomy, there are no cortical tags to grab onto with the irrigation/aspiration port.

Discussing a laser-assisted case, Dr. Maloney pointed out how the cortex peels off in tiny fragments and the particular difficulty of removing subincisional cortex.

Discussing anterior capsular tears, Dr. Maloney observed that with improved technology and surgeon experience, the rate of anterior capsular tears with LRLS has been dramatically reduced.

However, this complication has not been eliminated, he said.

Dr. Maloney explained that the tears can arise if the laser has not created a free-floating capsulotomy because any irregularity in the rim can radialize as the surgeon works to break the adhesions.

However, the tear can also develop even before the eye is opened because the nucleus might prolapse forward due to pressure created by intralenticular gas bubbles.

Dr. Maloney also showed cases where the anterior capsule tear extended to the posterior capsule, and depending on their extent, necessitated a change in the plan for IOL implantation.

Despite these challenges, Dr. Maloney said he still believes that LRLS is the safest way to perform cataract surgery in most patients.

Michael Lawless, MD

E: michael.lawless@visioneyeinstitute.com.au

Dr. Lawless is an Alcon Laboratories’ advisory board member.

Robert K. Maloney, MD

E: info@maloneyvision.com

Dr. Maloney is a consultant for Abbott Medical Optics.

Dr. Lawless and Dr. Maloney each were assigned to discuss opposing views of the relative safety of laser refractive lens surgery during Refractive Surgery Subspecialty Day at the 2013 meeting of the American Academy of Ophthalmology.

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