EyeWorld Asia-Pacific June 2011 Issue

June 2011 18 EW FEATURE EyeWorld speaks to experts about the role of combined phaco and LRI to correct astigmatism W hen it comes to managing astigmatism at the time of cataract surgery, there are basically two options: use a limbal relaxing incision (LRI) or a toric IOL. At present, most doctors would prefer to use a toric implant and then an LRI as a second choice, said Louis D. “Skip” Nichamin, MD, medical director, Laurel Eye Clinic, Brookville, Pa., USA. LRIs have less predictability and efficacy when compared to toric lenses, according to Edward J. Holland, MD, professor of ophthalmology, University of Cincinnati, and director, cornea service, Cincinnati Eye Institute, Cincinnati, Ohio, USA. There is also regression with LRIs. Tissue response to the procedure can’t be controlled, he said, so sometimes surgeons get exact corrections and other times they get undercorrections. Rarely do they get overcorrections, he said. In addition, the surgeon can create epithelial defects with LRIs and increase post-op dry eye. “Because toric lenses have great efficacy and minimal complications, they are the new dominant procedure to manage astigmatism,” Dr. Holland said. Unlike most doctors, however, Dr. Nichamin said he prefers the LRI to toric lenses. He’s very comfortable with the technique, as he has performed incisional keratotomy since the late 80s, he explained. He transitioned from what used to be called astigmatic keratotomy or AK2 in the early and mid-90s. “Some doctors don’t believe in LRIs because they think that they regress and are unpredictable, but they’re not. We have 10- to 15-year data that shows how well these work, but it is a specific surgical technique that one cannot take lightly. It has to be done properly,” Dr. Nichamin said. In addition, in the United States, without any toric premium or presbyopia-correcting IOL options, surgeons are limited to one toric IOL, he said. “As such, I continue to use a lot of LRIs, at least to debulk if not to completely eliminate the astigmatism. If it remains after the LRI, then we turn to the excimer laser to further enhance the result,” he said. Even with most doctors preferring the toric lens to the LRI to correct astigmatism, the incisional technique has not been completely replaced. When implanting a patient with Fixing astigmatism: Toric lens or LRI? by Enette Ngoei EyeWorld Contributing Editor When performing LRIs, the main points are careful positioning, careful measurements, and careful placement Source: Louis D. Nichamin, MD Assoc. Prof. CHEE Soon Phaik, MMed(Ophth), FRCS(G), FRCS(Ed), FRCOphth Senior Consultant, Singapore National Eye Centre 11 Third Hospital Avenue, Singapore 168751 Tel. no. +65-62277255 Fax no. +65-62277290 chee.soon.phaik@snec.com.sg M y experience with LRIs for close to a decade has been good outcome for the first 6 months, but, thereafter, variable regression. Careful slit-lamp biomicroscopy not unexpectedly reveals a narrowing and apposition of the incision created. While these incisions can be reopened at the slit lamp, none of my patients has been courageous enough to consent! Placing the incision on the steep axis and opposite clear corneal incisions are other options for correcting low amounts of astigmatism that have been of limited value in my practice. Unfortunately, successful LRI is achieved not by simply perfecting the surgical technique but, more importantly, in managing the postoperative wound healing. I prescribe topical steroids for 6-8 weeks post-surgery to prevent premature wound closure and regression. Important points to observe in the LRI technique are appropriate depth, the angle and location of the incision. Although it is more convenient to use a fixed depth LRI diamond blade, targeting 90% depth of the pachymetry reading on the table is ideal. Placing the incision within and parallel to the limbus, avoiding limbal vessels and incising perpendicular to the plane of the cornea are crucial to success. Inadvertent breaching of blood vessels results in undesired rapid healing of the incision. Incising obliquely results in less relaxing of the cornea than intended. The advent of toric IOLs has made the correction of astigmatism during cataract surgery more predictable than have LRIs. Important steps required to achieve good outcome include accurate marking of reference points, accurate alignment of the IOL, a capsulorhexis that completely overlaps the optic and complete removal of viscoelastic from behind the IOL. I use a freehand technique to mark the four cardinal reference points with the patient seated on the operating table with both eyes level with the aid of loupes. The additional two reference marks serve as a check for erroneous marking. I routinely check the outcome postoperatively using a wavefront analyzer (Topcon KR-1W, Tokyo, Japan) which provides the corneal and IOL astigmatism power and axis separately. Correcting astigmatism becomes even more crucial when using a multifocal IOL. Before toric multifocal IOLs became available, I combined LRI with a multifocal IOL and excluded patients with astigmatism exceeding 2 diopters as regression was an issue. Nowadays, my choice is a toric multifocal implant for corneal astigmatism starting at 0.75 diopters. In conclusion, I prefer fixing astigmatism with a toric lens because of its safety, efficacy and predictability. Editors’ note: Prof. Chee is a consultant for Bausch and Lomb (Rochester, NY, USA) but has no financial interests related to her comments. Views from Asia-Pacific a multifocal lens, for instance, surgeons manage the astigmatism with LRIs, Dr. Holland said. Additionally, in cases of high astigmatism where a patient’s astigmatism exceeds the power of the toric lens, LRI is combined with toric lens implantation, he said. The technique Combining phacoemulsification with an LRI is a routine, well-