A large body of previously published data in the peer-reviewed literature shows that femtosecond laser-assisted cataract surgery (LRLS) offers safety advantages over manual surgery.
However, physicians who perform laser-assisted surgery must be clear that selecting the right cases is critical if they are to take advantage of its safety benefits.
“If we can control unpredictable events, achieve greater precision, reduce damage to surrounding tissue, introduce options that were previously difficult to perform, and all of the above can be repeated exactly, then we will have a safer surgical approach,” said Dr. Lawless, who is the chief physician at the Eye Institute of New South Wales, Australia. chief physician and clinical senior lecturer in ophthalmology at the University of Sydney School of Medicine.
“The overwhelming evidence from the peer-reviewed literature suggests that LRLS surgery is safer than manual surgery,” he said.
During his presentation time, Dr. Lawless shared 74 papers reporting the effectiveness of LRLS, four were randomized controlled trials, 12 were longitudinal controlled studies, seven provided Level A or B evidence and seven provided Level C evidence.
Summarizing all the results, Dr. Lawless concluded that a more precise and predictive corneal incision can be made using the laser. Also, laser anterior capsulotomy is more precise than manual capsulotomy.
Dr. Lawless also noted that there are some studies that suggest that laser anterior capsulotomy does not provide good continuity of the cut surface.
However, these studies used older generation laser devices, which require higher energy than those used today. Recent findings show that when anterior capsulotomy is performed using a lower energy (7 microjoules), the laser breaks the capsulorhexis with a similar continuous performance of the capsulorhexis edge as manual capsulotomy.
“The lasers we use now are all low energy, and many devices are even lower than 7 microjoules,” said Dr. Lawless, who expects that many laser devices will soon produce bursal margins that meet or exceed the results of manual bursal tearing. The relationship between capsular rim quality and anterior capsule integrity remains to be demonstrated.
Many studies have shown that laser-assisted cataract surgery uses ultrasound energy in 40 to 90 percent less time. Also, several studies have shown that reducing ultrasound energy reduces endothelial cell loss.
In addition, there are two studies and many case reports showing a reduced chance of macular edema after laser-assisted surgery. There are also a number of case series studies suggesting that laser-assisted helps with more difficult procedures, including total cataract, cataract-dilated glaucoma, post-corneal transplantation, and those cases requiring mechanical pupil dilation.
With regard to surgical complications, Dr. Lawless cited his literature on a prospective study analyzing postoperative outcomes in 1500 eyes. Using published manual surgery data as a benchmark, Dr. Lawless found that the incidence of laser surgery posterior capsule tears, both with and without vitreous detachment, and anterior capsule tears were significantly lower than the best results in the published literature.
The incidence of posterior capsule complications using laser assistance (with vitreous detachment in 0.08% or 0.23% of cases) was also much better than the previously reported 2% incidence (analysis of data from 600,000 eyes in the Swedish Cataract Registry), Dr. Lawless said.
“In my personal case of 981 eyes, anterior capsule tears occurred in 0.1% of cases, and the incidence of posterior capsule tears was 0. I have never had such results in manual surgery.” He said.
Contrary voices: Laser surgery is not as safe as manual surgery
Dr. Maloney began by stating his preference for laser surgery. He has routinely performed LRLS for two years and has used three of the four devices available in the United States.
However, he also mentioned the complications encountered with all three devices and emphasized that lasers also introduce different safety issues. He cites Dr. Lawless’ literature, which highlights some curve issues with laser-assisted surgery.
In addition, Dr. Maloney used surgical videos to recreate the potential risk of anterior capsule tearing that can occur with the laser during cortical aspiration and small-pupil eye surgery.
“I try to avoid performing femtosecond laser surgery on patients with small pupils because for these patients, the femtosecond laser may face greater difficulties,” said Dr. Maloney, who is a clinical professor of ophthalmology at the Jules Stein Eye Institute at UCLA and director of the Maloney Vision Institute . “In addition, surgeons should be aware that these patients will have more difficulty with laser-assisted surgery, both during cortical aspiration, a condition that has rarely been reported before.”
He explained that in laser-assisted surgery, the water separation is done by separating the cortex from the central nucleus, not from the capsular bag, and it is difficult for the I/A head to grasp the cortex after the laser performs an anterior capsulotomy.
In discussing laser-assisted surgery cases, Dr. Maloney talked about how to remove small pieces of cortex and found it particularly difficult to aspirate the subincisional cortex.
When discussing anterior capsule tears, Dr. Maloney observed that as technology improves and surgeons gain experience, the incidence of anterior capsule tears in LRLS surgery will decrease significantly.
However, this complication has not been eliminated, he said.
Dr. Maloney explained that anterior capsule tears will occur if the laser does not create a free-floating anterior capsule membrane, as any irregularity in the incision margin will increase the risk of tearing.
However, because the pressure created by the air bubbles within the lens allows the nucleus to dislodge anteriorly, this can cause the tear to continue to develop before the eye opens.
Dr. Maloney also showed cases where the anterior capsule tear extended into the posterior capsule, and depending on the extent of the tear, the final decision on the type and option of IOL implantation was made.
Despite these challenges, Dr. Maloney continues to believe that LRLS is one of the safest surgical approaches for most cataract patients.