Eyeworld

EW FEATURE 48 by Enette Ngoei EyeWorld Contributing Editor Femtosecond laser: The cutting edge of corneal transplant surgery corneal surgeons. According to a retrospective study by Roger F. Steinert, M.D., professor of ophthal- mology, University of California, Irvine, and colleagues, the femtosec- ond zigzag incision PK induced 1.5 D less astigmatism than the conven- tional technique, on average. In fact, Dr. Steinert said he and colleagues have found that laser in- cision patients seem to have a more geometrically symmetrical astigma- tism rather than pure higher-order aberrations as compared with tradi- tional PK patients. "That's important as it makes [the astigmatism] easier to address with either astigmatism surgery or LASIK or with toric IOLs," he said. Patients with more astigmatism than they would like have more op- tions for improving their vision, he said. Faster healing Dr. Steinert and colleagues showed that for patients who have the po- tential for good results, that is, they don't have unhealthy retinas, two- thirds will obtain driver-like vision in the operated eye with glasses by the third post-op month. This is a big advantage over conventional corneal transplant patients who need a minimum of 6 months to a year before they have any useful vi- sion in the operated eye, Dr. Steinert said. Probably the biggest reason for these improved results with the laser incision compared to traditional trephine incision PK is that the laser incision allows for more complex in- cisions. As a result, there's much more surface area, the incision can be made without having tightened sutures to cause distortion, and pa- tients recover their useful vision a lot faster, Dr. Steinert said. If the sutures are a problem in terms of distorting the cornea, they can be taken out faster and can be- come stable faster. In many cases, sutures can be completely out within a year, if they need to be re- moved. Dr. Steinert said his personal policy is if a suture's not causing a problem, he will leave it in place. That said, Dr. Steinert and col- leagues presented a paper at the 2011 ASCRS•ASOA Symposium & Congress that found that patients who had their sutures removed did not have significantly different astig- matism when compared with pa- tients whose sutures remained. Dr. Steinert said that this find- ing showed that the good results from the femtosecond zigzag inci- sion PK had nothing to do with how the sutures were being made. Beyond femtosecond- assisted PK A newer technique to which the femtosecond laser has brought im- provements is deep anterior lamellar keratoplasty (DALK). While fem- tosecond lasers are not yet a great way to perform the lamellar dissec- tion across the central part of the cornea, according to Francis W. Price Jr. M.D., founder, Price Vision Group, Indianapolis, they have been very helpful in wound construction. Instead of using a metal trephine, surgeons can do the side cut or side incision using the fem- tosecond laser, Dr. Price said. Like for PK, there are a variety of wound constructions that can be done, such as the zigzag, the top hat, and the mushroom incision. "I think the best incision right now is the zigzag," Dr. Price said. Introduced by Marjan Farid, M.D., assistant professor of ophthal- mology, University of California, Irvine, the zigzag incision with the femtosecond laser for DALK allows the surgeon to perform pachymetry. February 2011 CORNEA May 2011 With the femtosecond-based zigzag technique for corneal transplant there is less corneal distortion Source: Roger F. Steinert, M.D. EyeWorld talks to experts about how the femtosecond laser has influenced keratoplasty A ble to cut corneal tissue at precise depths and in a variety of patterns, the femtosecond laser has brought significant im- provements to the outcomes of corneal transplantation surgery since its introduction. Penetrating keratoplasty (PK), one of the more established tech- niques, has benefited greatly from the technology. The technically challenging conventional method of PK using a trephine blade often re- sults in poor wound healing and se- vere astigmatism with post-op visual acuity less than optimal. With the femtosecond laser, however, sur- geons can create incision patterns that provide a broader surface area, resulting in a faster recovery of best corrected visual acuity and less in- duced astigmatism when compared to the conventional blade trephina- tion incision. The zigzag incision in particular has gained much popularity among AT A GLANCE • The biggest reason for improved results with the laser incision com- pared to traditional trephine inci- sion PK is the laser incision can be made more complex so there's more surface area, and the incision can be made without having tight- ened sutures to cause distortion; patients recover their useful vision a lot faster • The femtosecond laser zigzag inci- sion for DALK allows surgeons to get down very deeply with a hand dissection, giving them a good ref- erence point. This is helpful be- cause there are some patients in whom surgeons cannot get a big bubble to form, like those who have undergone radial keratotomy • Private insurance carriers are trying to refuse to pay for anterior grafts and especially deep anterior lamel- lar procedures continued on page 50

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