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Femtosecond lasers advance safety, efficacy and accuracy of cataract surgery
The technology lets surgeons create precise capsulotomies that maximize lens position and improve refractive outcomes.
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ATLANTIC CITY, N.J. — Femtosecond laser technology continues to make strides in cataract surgery, despite several drawbacks, according to a speaker here.
Delivering the cataract keynote address at the SUNY Downstate Current Concepts in Ophthalmology meeting, Eric D. Donnenfeld, MD, OSN Cornea/External Disease Board Member, shared pearls on femtosecond cataract surgery.
“I think this is the natural evolution of refractive cataract surgery,” Donnenfeld said. “I think it’s a technology we’ll all be embracing in the very near future.”
Advantages of femtosecond laser cataract surgery include reduced phacoemulsification power and time, improved incision design, reduced surgically induced astigmatism and the potential for reduced risk of postoperative endophthalmitis, Donnenfeld said.
Disadvantages of current phacoemulsification include vitreous loss, difficulty creating limbal relaxing incisions and a lack of precision, he said.
“Current cataract surgery is just not as precise as we’d like it to be,” Donnenfeld said. “Eventually, cataract surgery will become as precise as LASIK, with 98% of our patients seeing 20/20 or better. But right now, we have about half of that accuracy and also about half the safety.”
Docking and dilation
Donnenfeld said that the use of topical gels or ointments can impede docking of the suction cone.
“The day I did my first femtosecond cataract surgery, I did my usual lidocaine gel prep to create topical anesthesia and none of the suction cones stuck to the eye. I couldn’t get suction on anybody. We learned for the first time that you can’t use gels when you’re doing this surgery,” Donnenfeld said.
Docking and suction also depend on patient cooperation, he said.
“The patient who is going to shake their head during the procedure will knock off the suction cone, and this is not going to be someone that you can do the surgery on,” Donnenfeld said.
Donnenfeld said he uses maximal dilation and a preoperative topical NSAID to prevent pupil constriction and, in cases of poorly dilating pupils, intracameral lidocaine and epinephrine with a Malyugin ring (MicroSurgical Technology).
Capsulotomy, lens fragmentation
A femtosecond laser enables the creation of an accurate capsulotomy, optimizing the effective lens position and subsequent refractive outcomes, Donnenfeld said.
“When the capsulotomy is too large, the lens vaults forward in front of the capsule, and the patient ends up being myopic because the lens is further away from the retina. Conversely, when a capsulotomy is too small, it’s pulled backward a little bit and the patient ends up being hyperopic,” he said.
Donnenfeld said that the capsulotomy should be free-floating, and hydrodissection should be performed gently to prevent capsular block syndrome.
“I usually do a very aggressive hydrodissection with a perfectly round capsulotomy. The fluid has no place to go. You get a capsular block syndrome. There’s no weak area. The lens will get pushed up, close off the anterior capsulotomy, and the fluid has no place to go but posteriorly,” Donnenfeld said.
Donnenfeld said he cores out the lens nucleus and aspirates the four lens quadrants with the WhiteStar Signature phacoemulsification system (Abbott Medical Optics).
“I go at this time to a venturi setting, which creates a continuous vacuum, and you don’t have to get complete occlusion of the lens for phacoemulsification and the lens nuclei just fly to the center. It’s a very controlled, very rapid phacoemulsification, even if you’re taking out a 3-plus nuclear sclerotic cataract,” Donnenfeld said.
Wound creation
The femtosecond laser can be used to create three-plane incisions, which reduce the risk of postoperative endophthalmitis and surgically induced astigmatism, Donnenfeld said.
Limbal relaxing incisions can be created more precisely with a femtosecond laser than with a knife, Donnenfeld said.
“I’ve always said that LRIs are more of an art form than a science. Now, you can really customize them to achieve more precise results,” he said. “The problem is, though, that the incisions, while they are now a science, the patients’ response to these incisions can vary very significantly. So, the patients still get average results, and you don’t get the accuracy of a toric IOL, for example, with these incisions. But you can adjust them now for the first time.”
Donnenfeld suggested the use of low energy to create arcuate incisions.
“When you make the incision and it’s not free-floating and it’s not completely dissected, it allows you to leave the incision and then open it up, either on the table with intraoperative aberrometry or postoperatively with refraction, so that you can actually adjust these incisions postoperatively,” he said. – by Matt Hasson