Eyeworld

39 EW FEATURE Editors' note: Drs. Lee, Mannis, and Rapuano have no financial interests related to their comments. Contact information Lee: lee0003@aol.com Mannis: mjmannis@ucdavis.edu Rapuano: cjrapuano@willseye.org 2500 Sandersville Rd., Lexington, KY 40511 USA Phone: 800-354-7848, 859-259-4924 Fax: 859-259-4926 E-Mail: sales@stephensinst.com www.stephensinst.com Femtosecond Laser Cataract Surgery Instruments S5-1535 LRI Enhancement Forceps Cross-action provides accurate spreading of incisions pre- or post-operatively, or during slit-lamp examinations. S4-1700 Femtosecond Spatula Double ended sizing and spear shaped, thin blunted tips offer versatility for opening primary and secondary femtosecond laser incisions. S4-1710 Femtosecond Chopper Special design chops femtosecond laser fragmented nuclei with its unique shaped tip. April 2015 Corneal lamellar surgical procedures a year where a traumatic injury blinds a PK patient from a corneal graft wound rupture and expulsion of ocular contents," he said. "These issues do not occur with EK proce- dures and thus represent the major reason why EK has become so popu- lar across the globe." Concerns over graft survival Although the majority of full-thick- ness transplants are successful, graft failure due to immune rejection or endothelial decompensation remain major issues. Many donor and re- cipient risk factors can contribute to these outcomes. On the recipient side, any- thing that affects the ocular surface adversely affects the success rate of transplants, Dr. Rapuano said, including ocular surface disease, se- vere dry eye, severe blepharitis, and lid problems. Glaucoma is also one of the biggest risk factors for graft failure, he said, because it contrib- utes to endothelial decompensation, and deep stromal vascularization has been linked to graft rejection. The donor risk factors for graft failure, however, are less clear. There has long been an age bias in graft selection—physicians tend to prefer younger corneas and as a result, many eye banks set an upper age limit of 65 years. The Cornea Donor Study (CDS) helped to eliminate some of that age bias by showing that older corneas (aged 66 to 75 years) had survival rates comparable to younger corneas (12 to 65 years). The CDS data helped to alleviate concerns over whether there will be an adequate supply of donor cornea tissue as the population ages, but more research is needed to deter- mine what donor risk factors are relevant for graft survival. The future of PK The physicians agreed that strate- gies to promote faster and stronger wound healing after PK would be a tremendous advancement in the procedure. Faster wound healing would mean that sutures could be removed earlier without fear of wound dehiscence, and visual recovery would be more rapid and predictable. "If we had a glue that we could use to secure corneal transplants, without all the sutures and the suture-related problems, that might be something that would improve full-thickness transplant care," Dr. Rapuano said. Using a femtosecond laser to create the PK wound is one tech- nique that could make strides in this direction. "Femtosecond PK could provide a stronger PK wound and allow for a more stable wound with the potential for earlier suture removal and faster visual recovery," Dr. Lee said. "Unfortunately, the economics of femtosecond lasers, the decreased surgical efficiency, and the similarities in outcomes to PK with corneal trephines have prevent- ed the technology from becoming more popular." "I think the femtosecond laser is an interesting idea," Dr. Rapuano said. "It's not very practical and didn't show significant improve- ment in clinical results, but there may be innovations in the future that show improved clinical results." The future of PK may also hinge on the evolution of deep anterior lamellar keratoplasty (DALK). In contrast to endothelial keratoplasty, DALK has had little impact on the indications for PK. Of the nearly 50,000 corneal transplant proce- dures performed in the U.S. in 2013, nearly half were EKs, while fewer than 1,000 were DALKs. "There are newer techniques evolving that will perhaps make DALK more reliably effective than it is right now, but it's still in a tremendous state of evolution," Dr. Mannis said. "DALK has traditionally been more popular internationally com- pared to within the U.S.," Dr. Lee said. "I think the U.S. will see an increased trend toward DALK for the surgical treatment of anterior corne- al conditions like keratoconus and anterior corneal dystrophies in the future as we learn more about DALK from our international colleagues." Regardless of refinements of lamellar techniques, there will always be a need for PK procedures, even if it is small. "I see it still hav- ing a significant place in the practice of cornea because not everyone's a good candidate for an anterior procedure or a posterior procedure," Dr. Rapuano said. "There are some training programs that are only do- ing both of those and not doing any PKs, and I think that doesn't provide full-service corneal care." EW

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