EyeWorld Asia-Pacific June 2012 Issue

37 EWAP REFRACTIVE June 2012 LRIs for the treatment of astigmatism (shown here) can have variable results, causing some surgeons to use the femtosecond laser to make arcuate incisions Source: Louis D. Nichamin, MD “We can make intrastromal ablations to treat low-level cylinder, where we don’t break through to the surface,” Dr. Donnenfeld said. “We can treat astigmatism in a reproducible way without cutting through the superior corneal nerve, without creating an epithelial defect, and without the discomfort of an incisional surgery.” Furthermore, there is no learning curve for the novice surgeon. The incision Dr. Donnenfeld or Dr. Solomon makes is the incision any surgeon in the world will make, regardless of experience. Femtosecond cost and lack of data Obviously, the femtosecond laser is not free and can cost upward of half a million dollars. This, said Dr. Donnenfeld, is the biggest disadvantage. “Any time we have a disruptive new technology that completely improves upon what we’re doing, there’s a cost associated with it,” he said. “There’s going to be some negatives with that side of the equation. But to me, the inherent accuracy and precision of the laser offsets any cost concerns.” “When the femtosecond first came out for LASIK, people said it added too much expense for very little reward or gain,” Dr. Solomon said. “I don’t think that is going to be an issue. In fact, if you look at market share, femtosecond lasers have the market share of LASIK. I think the cost has worked itself out. I think patients are interested in refractive outcomes. If the femtosecond lasers provide better refractive outcomes for cataract surgery, then the market share will grow. Of course, that has yet to be determined.” Data directly comparing refractive outcomes of manual LRIs and femtosecond-made arcuate incisions is not yet available, but studies are in the works. There is data on femtosecond incisions, however. “We presented the first study of laser femtosecond cataract surgery looking at the cylinder,” Dr. Donnenfeld said. “There was a 70% reduction in astigmatism in patients treated with the femtosecond laser using the Eric Donnenfeld nomogram with a 33% reduction. This compares very favorably to anything in the literature.” “If we’re wondering about the variability of LRIs, if part of it has to do with not achieving a consistent arc and consistent shape and depth, the femtosecond laser takes all that out of it,” Dr. Solomon said. “Whether that will translate into more consistent outcomes with the management of astigmatism has yet to be seen. One thing we do know is we’re having to back way off of a standard LRI nomogram with [femtosecond] arcuates. I’m taking the Donnenfeld nomogram and reducing it by a third because we’re getting too much of an effect. Clearly, the arcuate incisions are working.” Dr. Solomon believes that there are enough femtosecond lasers for cataract surgery used around the globe that ophthalmologists should start seeing more data at the ASCRS•ASOA Symposium & Congress this spring and the American Academy of Ophthalmology meeting this fall. “Whether they’ll be comparing the two or even more importantly just showing good, consistent results with astigmatism is going to be a huge advance in the treatment of astigmatism at the time of cataract surgery,” he said. “I think the concept that WANG Zheng, MD Professor of Ophthalmology, Zhongshan Ophthalmic Center, 54 South Xianlie Road, Guangzhou, Guangdong 510060, China Tel. no. +86-20-87330381 gzstwang@gmail.com A s state-of-the-art cataract surgery is becoming a refractive procedure, there is no reason to leave corneal astigmatism untreated, especially for premium lenses and presbyopic lenses. Residual astigmatism, particularly the oblique and against-the-rule ones, greatly compromise the advantages brought by these lenses. More and more cataract surgeons are considering the influence of corneal astigmatism on post-op outcomes while planning their cataract operations. They may determine the position, the shape, and the length of the corneal incision according to the amount and the axis of the astigmatism. But as far as I know, not many of them actually perform surgery to correct astigmatism lower than 1 D during the operation. Awareness is a factor. The unpredictable result of manual arcuate incisions or LRIs is a more important factor. Obviously, the femtosecond laser is much more accurate and precise than a diamond knife in terms of the placement and depth of the corneal cut, improves reproducibility, and is safer. Of course, a new nomogram has to be worked out. But I doubt that arcuate incisions would be as accurate as astigmatic LASIK or PRK eventually. After all, the correcting effect is an indirect result of the corneal biomechanical changes induced by the corneal cuts. The effect may be related to some other factors other than the parameters of the corneal cuts. There’s also an individual variation in the biomechanical property of the cornea, of which our knowledge is very limited at this time. However, the beauty of the arcuate incision is that, unlike LASIK or PRK, it spares the optical zone and therefore the visual quality is not deteriorated after surgery. Cost is an issue now. But if a real benefit can be shown, femtosecond arcuate incisions will be accepted by more and more surgeons and patients. Editors’ note: Prof. Wang is a consultant for Technolas Perfect Vision (Munich, Germany). Views from Asia-Pacific the femtosecond laser provides a more efficient, customizable, and adjustable way to do an astigmatic keratotomy is exciting,” Dr. Donnenfeld said. “This will remove the inconsistencies of the astigmatic procedure. It will also bring many ophthalmologists who aren’t doing LRIs now into this, which will offer them the ability to participate in presbyopic IOL surgery.” EWAP Editors’ note: Drs. Donnenfeld and Solomon have financial interests with AMO and Alcon (Fort Worth, Texas, USA/Hünenberg, Switzerland). Contact information Donnenfeld: eddoph@aol.com Solomon: kerry.solomon@carolinaeyecare.com