Eyeworld

May 2014 by Maxine Lipner Rigging the transplantation game in ophthalmologists' favor IMPORTANT SAFETY INFORMATION FOR CENTURION® VISION SYSTEM CAUTION: Federal (USA) law restricts this device to sale by, or on the order of, a physician. As part of a properly maintained surgical environment, it is recommended that a backup IOL Injector be made available in the event the AutoSert® IOL Injector Handpiece does not perform as expected. INDICATION: The CENTURION® Vision System is indicated for emulsification, separation, irrigation, and aspiration of cataracts, residual cortical material and lens epithelial cells, vitreous aspiration and cutting associated with anterior vitrectomy, bipolar coagulation, and intraocular lens injection. The AutoSert® IOL Injector Handpiece is intended to deliver qualified AcrySof® intraocular lenses into the eye following cataract removal. The AutoSert® IOL Injector Handpiece achieves the functionality of injection of intraocular lenses. The AutoSert® IOL Injector Handpiece is indicated for use with the AcrySof® lenses SN6OWF, SN6AD1, SN6AT3 through SN6AT9, as well as approved AcrySof® lenses that are specifically indicated for use with this inserter, as indicated in the approved labeling of those lenses. WARNINGS: Appropriate use of CENTURION® Vision System parameters and accessories is important for successful procedures. Use of low vacuum limits, low flow rates, low bottle heights, high power settings, extended power usage, power usage during occlusion conditions (beeping tones), failure to sufficiently aspirate viscoelastic prior to using power, excessively tight incisions, and combinations of the above actions may result in significant temperature increases at incision site and inside the eye, and lead to severe thermal eye tissue damage. Good clinical practice dictates the testing for adequate irrigation and aspiration flow prior to entering the eye. Ensure that tubings are not occluded or pinched during any phase of operation. The consumables used in conjunction with ALCON® instrument products constitute a complete surgical system. Use of consumables and handpieces other than those manufactured by Alcon may affect system performance and create potential hazards. AEs/COMPLICATIONS: Inadvertent actuation of Prime or Tune while a handpiece is in the eye can create a hazardous condition that may result in patient injury. During any ultrasonic procedure, metal particles may result from inadvertent touching of the ultrasonic tip with a second instrument. Another potential source of metal particles resulting from any ultrasonic handpiece may be the result of ultrasonic energy causing micro abrasion of the ultrasonic tip. ATTENTION: Refer to the Directions for Use and Operator's Manual for a complete listing of indications, warnings, cautions and notes. © 2013 Novartis 9/13 CNT13017JAD New strategy for boosting high-risk corneal graft success U nfortunately, current odds are that if a patient rejects a corneal transplant, he likely will not do any better the next time, ac- cording to Jerry Y. Niederkorn, PhD, professor and vice chair of research, Department of Ophthalmology, UT Southwestern Medical Center, Dallas. For first-time recipients, there is about a 10% rejection rate, and if the patient has a second transplant, the rejection goes up to 35% or even higher. This rate continues to rise with each subsequent graft, he said. However, all that could change based on the work of investigators who have found a way to boost corneal transplant acceptance rates. New study results published in the December 2013 issue of the American Journal of Transplantation indicate that if tissue matching is done in conjunction with blocking an immune molecule called inter- feron gamma, it is a whole different story, Dr. Niederkorn said. In this case, results mimic the acceptance rate of those undergoing a first-time transplant, without the aid of steroids. In the United States, tissue matching is not normally utilized for corneal transplants. "The cornea is selected for transplantation based on its overall quality of the tissue and the integrity of the endothelial cell layer on the corneal button," Dr. Niederkorn said. Playing two cards The study findings were serendipi- tous, Dr. Niederkorn explained. Investigators were actually looking at the role of a category of lympho- cytes called Th1 cells, which pro- duce interferon gamma. "Interferon gamma is also the molecule that was believed to be important for con- tributing to graft rejection," he said. Investigators set out to conduct studies mimicking what would be done in humans, forgoing tissue matching in the mice used for the trials. "The hypothesis was if we neutralize or block the interferon gamma, we will block rejection," Dr. Niederkorn said. "We did that, but we found the exact opposite." Typically in mice without any tissue matching, and without the use of steroids, there is a 50% graft acceptance rate, Dr. Niederkorn said. But when the interferon gamma was blocked with an antibody or when mice without the interferon gamma gene were used, success rates plum- meted. "In both cases instead of having a better success rate and im- proved survival, we had no survival because the grafts underwent rejec- tion," he said. Investigators then examined what would happen if they matched the donor and the recipient at the major histocompatibility complex (MHC), which in humans is known as HLA typing. "That's what's done normally with all other forms of transplanta- tion except the cornea," he said. When this was done in conjunction with blockage of interferon gamma, they were surprised to find almost no rejection. "We found 10% or less rejection," Dr. Niederkorn said. He added that this was the exact oppo- site of what happened when inter- feron gamma alone was blocked without MHC matching, in which there was 100% graft rejection. By doing these steps simultane- ously, there was an acceptance rate in the mice that mimics what hap- pens with first-time human corneal transplant patients, who are also re- ceiving steroids. "Our point of view is if your patient is going to get a second transplant, you have a lot of problems in a normal setting," Dr. Niederkorn said. "Our study would suggest that if you first do MHC matching and block interferon gamma, you should have a very good acceptance rate." Long-range game Investigators are now working to see how they can best block interferon gamma in humans. In mice this is given systemically, Dr. Niederkorn said. "You would not want to do that in a patient unless you had a high- risk patient who had lost vision in both eyes or something of that na- ture," he said. "What we're starting on now is seeing if we can give this in eye drop form to have a local effect." Also, investigators are now try- ing to determine for how long the interferon gamma would need to be blocked. "It's very feasible if we block, once the graft has healed we could terminate treatment and the graft will survive," Dr. Niederkorn said. When tissue matching is done in conjunction with blocking interferon gamma graft, acceptance goes up. Source: Jerry Y. Niederkorn, PhD

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