March 2021

REFRACTIVE

Using AK/LRIs to correct astigmatism


by Ellen Stodola Editorial Co-Director

 

Manual LRI performed at the slit lamp

Femtosecond LRI
Source (all): Eric Donnenfeld, MD

 

With many new premium lens technologies and increased patient expectations, astigmatic keratotomy (AK) and limbal relaxing incisions (LRIs) are tools that can be used by surgeons to help correct low levels of astigmatism. Eric Donnenfeld, MD, and Robert Weinstock, MD, discussed how they use these to improve outcomes.
LRIs are made to widen the cornea in certain areas to reduce astigmatism, Dr. Donnenfeld said. The purpose is to reduce astigmatism by flattening the steep axis of the cornea. “The analogy I make to patients is it’s similar to cutting the laces on a football,” he said. “If you do that, it would round out to become more basketball shaped, which is similar to what you want to do to reduce astigmatism.”
Dr. Donnenfeld that he’s using LRIs more than ever in his practice because patients have higher expectations. “They expect better uncorrected vision after LASIK and cataract surgery.”
Dr. Donnenfeld said that over the last several years, his use has shifted. Previously, these incisions could be used for higher levels of astigmatism. Now, there are specific technologies, like toric IOLs, that can be used to correct higher levels of astigmatism. However, he noted that LRIs are still valuable to correct astigmatism from 0.5 D up to 1–1.25 D. “I use them in patients who’ve had LASIK who have a spherical equivalent close to plano but have astigmatism,” he said, adding that he also uses them for patients who had cataract surgery and have astigmatism after. “It’s a simple procedure, and you get an almost instantaneous response.”
According to Dr. Weinstock, astigmatism management has become one of the hottest topics in cataract and refractive surgery. As cataract technology has improved, IOL implants have improved, as well as biometry, he said, adding that it’s approaching standard of care to address astigmatism at the time of cataract surgery.
“Typically, a single arc, pair of arcs, or even double pair of arcs were used to correct with a diamond blade,” he said. This was before toric IOLs were released. Dr. Weinstock noted that toric IOLs can be used to correct higher amounts of astigmatism, but he said that most patients tend to have lower amounts of astigmatism.

Manual vs. femtosecond laser technique

Dr. Donnenfeld said surgeons can employ a manual technique or use a femtosecond laser for LRIs/AKs. Both of these options may still be needed. The femtosecond laser gives access to a technology that allows surgeons to perform a surgery as efficaciously, as accurately, and as safely as they can, he said.
Femtosecond lasers can do something that manual LRIs can’t do in that you can do intrastromal incisions with the femtosecond laser, Dr. Donnenfeld said. The incision is made in the stroma, and there is no pain, no disruption of the epithelium, no gaping wound, and it doesn’t cut the cornea nerve. There is also no need for topical antibiotics.
However, Dr. Donnenfeld said he would use a manual technique for patients having cataract surgery who aren’t financially comfortable getting a premium IOL. For these patients, adding a manual LRI to surgery is an added value, he said.
Dr. Donnenfeld said he will also use a manual technique for patients who’ve had LASIK or cataract surgery, and he will use a diamond knife at the slit lamp. “It’s a simple, 1-minute procedure,” he said. “The patient leaves the office seeing better almost immediately.”
If you don’t have a femtosecond laser, a manual LRI is very reasonable to do, Dr. Donnenfeld said, as long as you understand the limitations of an LRI. These are wonderful for low levels of astigmatism, but for higher levels, there are other things that are better, he said.
When the femtosecond laser came along, it became more accurate to use it to make these incisions to correct astigmatism, Dr. Weinstock said, adding that many surgeons use the femtosecond laser for the bulk of their patients.
It’s important to have AKs/LRIs at the right axis, Dr. Weinstock said, and many laser companies are including features to help with this. He added that ORA (Alcon) and Callisto eye (Carl Zeiss Meditec) can be used during surgery for placement at the right axis (or a marking pen can be used preoperatively).
Some surgeons prefer to open the incisions up at the time of surgery to give them more effect, he said, while others like to open up afterward, depending on how the patient is doing. “Sometimes the arcuate incision alone does the correction and you don’t have to open them,” Dr. Weinstock said. “But sometimes you need to open them.” He prefers to not open the incisions during surgery but waits to see the patient in a month. “If the astigmatism is not gone, I’ll open the incision up at the slit lamp and check them,” he said. “Sometimes I’ll even augment it manually at the slit lamp with a diamond blade and either extend the incision or make another incision.”
If patients are signing up for premium cataract surgery, it’s the responsibility of the surgeon to not just do great surgery but also to follow them postop and do the enhancement that may be needed, Dr. Weinstock said.
He mentioned that sometimes there may be a break in suction or another situation where a femtosecond laser can’t be used. In these cases, he will use a manual technique.
If a surgeon doesn’t have access to a femtosecond laser, they can easily practice on pig eyes or artificial eyes and incorporate manual LRIs into their surgical routine, Dr. Weinstock said, adding that the technique for doing manual incisions is not difficult.

Nomograms

Going back 30 years, Dr. Weinstock said that Dr. Donnenfeld, Louis Nichamin, MD, and Richard Lindstrom, MD, were among those doing AKs using a diamond blade. They developed nomograms depending on how much astigmatism there was and what optical zone the arc would be at, and how long the arc would be and how deep the cut would be in the cornea depending on the localized pachymetry of the cornea. The longer arc length, the more astigmatism was being corrected.
“If you don’t have access to a femtosecond laser, [you can fall] back on the Donnenfeld or Nichamin nomogram with a diamond blade during surgery at the beginning or end of the case,” Dr. Weinstock said.
Dr. Donnenfeld said he uses the Donnenfeld nomogram and that this is available on the CATALYS femtosecond laser platform (Johnson & Johnson Vision).
Dr. Donnenfeld also said a good place to learn about limbal relaxing incisions is www.lricalculator.com, which he designed about 10 years ago. It gives doctors the nomogram and allows them to populate their patients’ treatments, so they know where to place the incisions, he said.
Dr. Donnenfeld stressed that LRIs are tools to take patients’ results from good to great. “I often will offer patients LRIs for even small amounts of astigmatism,” he said. “My goal for refractive cataract surgery is not to make people happy but to exceed their expectations, and limbal relaxing incisions are one of the most important ways that I can exceed patients’ expectations by reducing astigmatism to lower levels.”

About the physicians

Eric Donnenfeld, MD

Ophthalmic Consultants of Long Island
Garden City, New York

Robert Weinstock, MD
Weinstock Laser Eye Center
Largo, Florida

Relevant disclosures

Donnenfeld
: Johnson & Johnson Vision
Weinstock: Alcon, Bausch + Lomb, Johnson & Johnson Vision, LENSAR

Contact

Donnenfeld: ericdonnenfeld@gmail.com
Weinstock: rjweinstock@yahoo.com

Using AK/LRIs to correct astigmatism Using AK/LRIs to correct astigmatism
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2021-03-02T11:54:15Z
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