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Bladeless cataract surgery largely hinges on precise capsulorrhexis design
A modified femtosecond laser optimizes effective lens position, with no posterior capsular rupture.
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Modifications to an approved femtosecond laser enabled the creation of an accurate and repeatable continuous capsular capsulorrhexis.
At the European Society of Cataract Surgeons meeting in Milan, Perry S. Binder, MD, explained how an IntraLase 150-kHz femtosecond laser (Abbott Medical Optics) with hardware and software modifications was used to create a smooth, round capsulorrhexis.
“We were very happy with the ability to create a complete, very round capsulorrhexis that we think is better than the current technology using manual forceps to create the capsulorrhexis,” Christopher L. Blanton, MD, one of the presentation authors, said in a follow-up interview with Ocular Surgery News.
Surgeons have wondered whether a femtosecond laser used to create LASIK flaps could also be used to create a capsulorrhexis, Blanton said.
Christopher L. Blanton
“That was done,” he said. “That’s a huge step forward for the platform in terms of being able to be one of the devices that people use to do [femtosecond laser-assisted] cataract surgery.”
At the ESCRS meeting, Binder presented results of a preclinical trial in which 67 capsulorrhexis procedures were performed on 35 cadaveric eyes with a modified IntraLase femtosecond laser. Results showed that almost all capsulotomies were round and smooth.
Bladeless cataract surgery
The IntraLase is already cleared by the U.S. Food and Drug Administration to create clear corneal incisions and arcuate incisions in corneal surgery including cataract procedures.
“Obviously, the last two components are going to be the ability to do a capsulorrhexis and to do some form of femto fragmentation of the lens,” Blanton said. “That’s basically what we’re working on. … What we’re trying to do is find the best system for creating a capsulorrhexis.”
Binder, Blanton and colleagues set out to create a capsulorrhexis that would round out a completely bladeless cataract surgery procedure, Blanton said.
“A lot of the current emphasis on the femtosecond laser platforms is geared toward doing bladeless cataract surgery,” he said. “[Capsulorrhexis] is the one element that most surgeons think is going to be the most important. The ability to do a very precise capsulorrhexis is going to minimize complications and also, we think, allow us to create a better effective lens position — in other words, to precisely place intraocular lenses so that some of the inaccuracies of the current IOL formulas go away or at least get better.”
Laser range finder
Some femtosecond laser systems use optical coherence tomography to determine capsulorrhexis depth. In the current study, the researchers used a laser range finder to locate the lens surface and orientation.
“What it’s able to do is measure how deep into the anterior chamber we need to go before we contact the capsule,” Blanton said. “You just have to make sure you’re underneath the capsule so that you get a complete, full-thickness capsulotomy or capsulorrhexis. Then, the next question is, depending on how deep you can go, how much fragmentation of the lens can you do?”
The femtosecond laser capsulorrhexis resulted in no cases of posterior capsular rupture, Blanton said.
“The precision of the device is good,” he said. “With some of the earlier platforms, there have been cases of posterior capsular rupture, probably due to increased pressure inside the bag, not from actual perforation by the laser, but still a significant complication.”
In addition, the investigators found that a liquid interface was more effective than flat or curved applanated patient interfaces, Blanton said. – by Matt Hasson