Laser cataract surgery (LCS) remains controversial. Surgeons who remain skeptical about whether the femtosecond laser has benefit now and if it holds any promise for the future should consider that evolution takes place in bursts and it takes time to critically evaluate new techniques and technologies after they are introduced, said H. Burkhard Dick, MD, PhD, who discussed advances in LCS at AAO 2018.
Dr. Dick, who is a recognized expert and leading researcher in LCS, reminded attendees that ultrasound cataract surgery has a greater than 50-year history. In contrast, femtosecond lasers for cataract surgery have been available for less than 10 years. During this relatively short time, there have been and continue to be both refinements leading to better outcomes and developments leading to new techniques.
“When new developments, devices, and techniques are critically evaluated in controlled clinical trials, they may be found to provide no improvement, be an incremental advance, or something that is truly better,” said Dr. Dick, Professor and Chair, Department of Ophthalmology, Ruhr University Eye Hospital, Bochum Germany.
“Based on such evidence, other surgeons will decide whether or not to offer the laser. I, however, am definitely convinced that it will lead to improved stratified patient care.”
In a symposium titled “The Era of Femtosecond Lasers,” Dr. Dick reviewed some of the most recent developments in LCS with a focus on randomized controlled trials conducted by his group. He reviewed one study showing that modifying the laser settings by increasing the vertical spot spacing from 10 to 15 microns was successful for improving the quality of the laser-cut capsulotomy and reducing the number of tags, which are associated with risk of radial tears.
A randomized study evaluating capsulotomy centration methods for LCS showed a benefit for optical coherence tomography (OCT)-based scanned capsule centration versus pupil centration. In addition, it provided evidence for guiding capsulotomy sizing to guarantee 360 degree capsule overlap of a 6 mm optic. The study’s results showed that the optimal size depended on the type of IOL: it was 4.7 mm for a 3-piece IOL, 4.9 mm for a single-piece IOL, and 5.1 mm for a plate haptic IOL, Dr. Dick reported.
Findings from another randomized study conducted by Dr. Dick and colleagues showed that LCS can improve the predictability of refractive outcomes compared with manual surgery. In the trial that included 100 patients who had LCS in one eye and conventional surgery in the fellow eye, achieved refraction at 6 months was within 0.5 D of target in 92% of LCS eyes versus 71% of eyes in the conventional surgery group.
“It appears that the advantage of the laser is subtle, but that is because standard cataract surgery is already that good,” Dr. Dick said.
He added that an additional benefit of using the laser for capsulotomy creation may be identified when it is used for surgeries involving the new and emerging capsulotomy-fixated IOLs.
Since it was first introduced, the applications of the femtosecond laser have expanded and now include marking of the target axis to guide toric IOL alignment. Initially developed for making corneal marks, the femtosecond laser is now being used to mark the capsule.
“Capsule marking is a unique technique that allows precise identification of the steep axis both intraoperatively and postoperatively if realignment is necessary,” said Dr. Dick.
“The capsule marks are stable and precise and provide a landmark for realigning the IOL without any need for remarking.”
Dr. Dick said he has also been using the femtosecond laser for primary posterior capsulotomy (PPC) in pediatric cataract surgery cases for many years. More recently, he began performing laser PPC in adult eyes as an off-label procedure. Performed as the last step in the surgery and guided by the device’s 3-dimensional OCT imaging system, the laser PPC keeps the anterior hyaloid intact and does not damage the IOL, Dr. Dick said.
A randomized study in adult eyes compared the laser PPC with routine manual cataract surgery without PPC. Published results showed laser PPC was a safe and feasible technique for preventing posterior capsule opacification over a 6-month follow-up period. Recently presented results from follow-up to 2 years showed Nd:YAG capsulotomy had been done in 12% of control eyes but in none of the eyes with a laser PPC.