Improving LRI Results

Two doctors discuss their techniques.

BY LESLIE GOLDBERG, ASSOCIATE EDITOR

Limbal relaxing incisions (LRIs) are one of the most valuable tools for maximizing astigmatic surgical outcomes during cataract surgery," says Eric Donnenfeld, M.D., F.A.C.S., a partner with Ophthalmic Consultants of Long Island, Rockville Centre, N.Y. Effective LRIs can also be a key factor in cataract patient satisfaction.

In this article, Dr. Donnenfeld and Farrell Tyson, M.D., F.A.C.S., of Cape Coral Eye Center, Cape Coral, Fla., will discuss their LRI techniques, complication management and pricing, as well as the pros and cons of this procedure.

Dr. Donnenfeld's Surgical Technique

"For LRI procedures, I choose a diamond knife. I prefer a 0.6-mm diamond knife and make my incisions 0.5 mm in from the limbus," says Dr. Donnenfeld. For small amounts of cylinder, he does not mark the cornea. For cylinder greater than 1 D, he will mark the axis with a modified Dell marker.

"We really only have three different types of incisions for LRIs," explains Dr. Donnenfeld. "We use one incision of 1.5 clock hours for 0.5 D. For 0.75 D, we use two paired incisions of 1 clock hour and for 1.5 D, we make two incisions 2 clock hours in length." He does not recommend LRIs alone for more than 2 D of cylinder because of the increased chance of irregular astigmatism. For cylinder over 2 D, Dr. Donnenfeld will perform LRIs and then excimer laser photoablation for the residual cylinder, waiting 1 month between procedures.

Next, Dr. Donnenfeld selects a nomogram. "There are a dozen good nomograms in the literature right now. Nomograms provide a very good basis for calculating the location and depth of your LRI. I have recently developed a nomogram called the Donnenfeld nomogram that can be found on the LRIcalculator.com Web site," he says.

The LRIcalculator.com site (Advanced Medical Optics, Santa Ana, Calif.) provides advice on how to perform LRIs and includes a video showing the technique. There is also a calculator that allows the ophthalmologist to insert patients' parameters. The LRI calculator will then tell doctors exactly where to make the incisions and how long to make them.

"I generally perform my LRIs in the OR at the start of cataract surgery and mark the cornea at the 12 o'clock position with the patient sitting up — and then mark my astigmatic axis on the table. I then use the modified Dell marker to make either a 1 or 2 o'clock incision that is centered over the astigmatic axis," says Dr. Donnenfeld. "I place the diamond knife into the cornea and hold for about 2 seconds to achieve maximal incision depth. Then, I press firmly and draw the knife toward myself for the desired length of the desired incision."

Dr. Donnenfeld says that the most common mistake that surgeons make is that they don't press hard enough while making the incision and only achieve an incision of approximately 50%, creating no astigmatic effect.

"Following the incision, I will generally use an NSAID and fourth-generation fluoroquinolone, then send the patient home with a fourth-generation fluoroquinolone to use q.i.d. for a week," he says.

Dr. Donnenfeld performs LRIs on approximately 35% of his cataract surgeries. "I perform LRIs under the operating microscope of an excimer laser. I also feel comfortable performing them at a slit lamp for small amounts of cylinder. I use a diamond knife that has an angled blade to allow easier access at the slit lamp," says Dr. Donnenfeld (Figure).

Complication Management

"One of the lesser-known aspects of LRIs is that for a surgeon to expertly perform an LRI, he has to take into consideration not only the preexisting cylinder but also the surgically induced cylinder created by his incision," says Dr. Donnenfeld. "These two factors create vector forces that have to be analyzed, resulting in a new axis and a new magnitude of astigmatism. If you induce half a diopter of cylinder, you are going to be changing the amount of correction needed during surgery."

He says it is very rare to have a perforation during an LRI procedure. For small perforations, Dr. Donnenfeld uses a contact lens. For larger perforations, a suture is needed. For undercorrections, he will either go back and re-deepen or lengthen his incisions. For patients who have overcorrected, he will either suture the wound or perform excimer laser photoablation for the residual cylinder but will never make an incision 90° away from his original incisions for fear of creating an irregular astigmatism.

Figure. A patient undergoing an LRI procedure at the slit lamp.

"LRIs are an extremely successful technique for reducing patient astigmatism and improving patient satisfaction with cataract surgery," concludes Dr. Donnenfeld.

Dr. Tyson's Surgical Procedure

The following are LRI techniques Dr. Tyson implements in order to achieve the best possible treatment results for his cataract patients. "I like using a 600 μm diamond blade because the deeper you go, the more effect with less arc is achieved, so you don't need to make as long a cut," says Dr. Tyson. "An arcuate cut or a T-cut can be used. The arcuate will get you more and the T-cut will get you less, but sometimes the T-cut is just easier to do. If I need more response, I will go with the arcuate.

"With my cataract patients, if the corneal topography, refraction and keratometry all match, I will perform the LRI at the time of surgery," says Dr. Tyson. If not, he will perform the cataract surgery and then do the LRI 1 month postop based on the refraction.

"I like to do the LRIs before I do any other procedure because I get a nice firm eye," says Dr. Tyson. "I use a fixation device and put it 180° from where I am doing the treatment. Then I will make my incision."

While some surgeons prefer to make their paracentesis and then fill the eye with viscoelastic, Dr. Tyson prefers to work on an eye that has been unaltered. "Viscoelastic makes the eye even harder. At the end of the case, the eye will be softer so that you may not get the same depth that you would with a firm eye." Dr. Tyson says that the eye also changes slightly during surgery, so he prefers to do the LRI at the beginning of the case.

"There is some discussion on marking the eye because of the chance for cyclorotation, but with LRIs there is always a little bit of variability so I am not as particular on marking the eye," explains Dr. Tyson. "I know when looking at the eyes I see the blood vessels coming in from 0° and 180° and I can tell where 90° and 45° is. We are not getting down to 1° or 2° of precision with LRIs. So with these patients, even if they cyclorotate a little bit, I can see where that 0° and 180° is."

Dr. Tyson says that LRI procedures are good for about 1 D to 2 D of treatment and that doctors can be off a little bit and still obtain the proper result because the eye naturally wants to regress to a spherical dome.

"With a toric lens, you are not relaxing anything," says Dr. Tyson. "The toric lens needs to be on-axis better, but the lenses only come in low powers of cylinder correction." He saves the toric lenses for patients who have 2 D or more of astigmatism because he wants to use the toric lens to knock down the astigmatism. "I'll use the LRI to get what remains at 1 month postoperatively. When treating less than 2 D of cylinder, I prefer to use a good aspheric lens with LRIs, so I can get the best IOL optics combined with astigmatism correction via LRIs," says Dr. Tyson.

Pricing

Dr. Tyson does not charge extra for LRI procedures. He wants his patients to have the best possible outcomes because, he says, happy patients drive word of mouth. He has both a presbyopia package and an aspheric package/toric package that has LRIs bundled into them, if needed.

Pros and Cons of LRIs

LRI procedures are very cost-effective, says Dr. Tyson. "The toric lens, on average, is about $400 extra to the ASC. With an LRI, the surgeon buys one diamond blade, for about $1,200, and that blade can last a long time."

One negative of the LRI procedure is that most surgeons are not trained in LRI surgery — it is an acquired skill.

"In addition, with LRIs when you get to the extremes, predictability falls off quite a bit," he says. "You may treat a patient and get an initial good effect and then they heal so well that they still have the astigmatism a month later. You want that relaxation, but some people heal so well that they return to the way they were. That is another reason that I don't charge — the unpredictability. I'd rather just perform the surgery and if I get it I'm a hero but if not, the patient is not disappointed." This only happens in about 5% of patients.

Overall, LRIs are a valuable tool to have in a surgeon's armamentarium as they help doctors to meet the expectations of today's demanding astigmatic patients. OM

Eric Donnenfeld, M.D., F.A.C.S. is a consultant for Allergan, AMO, Alcon and Bausch & Lomb. Toby Tyson, M.D., F.A.C.S., reports no financial interest.