Eyeworld

EW CORNEA 56 March 2016 by Liz Hillman EyeWorld Staff Writer Literature review reveals successes, shortcomings, and areas for future KPro research A recent literature review that evaluated the out- comes and complications of the Boston type 1 keratoprosthesis (KPro, Massachusetts Eye and Ear Infirmary, Boston) found that overall success of the device in patients is significantly better than in early trial years but noted that there are still some seri- ous complications to address. This Ophthalmic Technology Assessment, prepared by the Amer- ican Academy of Ophthalmology (AAO) and published in its jour- nal Ophthalmology, looked at 22 peer-reviewed studies to answer the question: "What are the outcomes and complications of the [KPro] for artificial corneal transplantation?" The KPro, which the Food and Drug Administration approved in 1992, is the "most commonly used artificial cornea in the United States and throughout the world," accord- ing to Massachusetts Eye and Ear In- firmary's website. Data from the Eye Bank Association of America's An- nual Statistic Report reveals that of the more than 76,400 corneal tissues used in transplants in 2014, slightly less than 300 were KPro cases. This, however, was a 15.3% increase over the KPro cases out of overall corneal tissue transplants reported in 2013. The prosthetic is composed of three parts: a polymethylmethac- rylate (PMMA) core with human cadaveric tissue (to help suture the device to the recipient cornea), sand- wiched between the front PMMA core and a plastic or titanium back plate. William Barry Lee, MD, Eye Consultants of Atlanta, said the KPro is not for every corneal trans- plant patient. "It is reserved for patients who have undergone multiple human ca- daveric corneal transplant rejections or for cases where human tissue would reject such as severe corneal neovascularization or total limbal stem cell loss," Dr. Lee said. Dr. Lee, the report's lead author, said that the overall findings reveal that the outcomes of the KPro have "certainly improved dramatically from some of the early publications with the device in the 20th centu- ry." Still, he added, the main chal- lenges of preventing infection and glaucoma control remain. Dr. Lee went on to say that while long-term topical antibiotic use has "dramatically reduced risk of infection," it's still possible and, in the end, could result in loss of the eye. Visual outcomes Based on the Snellen chart, patients in 14 of the 16 articles that reported visual acuity had preoperative vision ranging from 20/100 to light percep- tion. After the procedure, Lee et al. found the majority reported vision at 20/200 or better. "In 10 of the 16 articles report- ing this information, 54% to 84% Report: KPro outcomes improved, but serious complications still significant T he Boston type 1 keratoprosthesis (KPro), approved by the Food and Drug Administration in 1992, is the most common artificial cornea used in the U.S. and worldwide. It has been credited with improving the vision in many patients who otherwise would suffer from corneal blindness. The design of the device has been improved upon since its conception, but like any prosthesis, there remain chal- lenges and major complications that can occur. Ophthalmologists who use the KPro should be aware of which patients are ideal candidates for the device and what alterna- tives there are prior to using the prosthesis, such as stem cell transplant for patients with severe limbal stem cell deficiency. Certain patients such as those with auto- immune conditions are more susceptible to severe complications leading to the loss of vision. The ability to manage the compli- cations, namely glaucoma and infections, among others, are crucial to the outcomes of patients. An in-depth discussion of the risks, alternatives, and benefits should be had with a patient so that informed consent is obtained thoroughly. This month's "Cornea editor's corner of the world" focuses on reviewing the reported outcomes and complications of the Boston type 1 keratoprosthesis. William Barry Lee, MD, the lead author of the paper published in the journal Ophthalmology, and Roni Shtein, MD, discuss what is revealed in the 22 peer-reviewed studies included in the review. Clara Chan, MD, FRCSC, FACS, cornea editor The clouded cornea of a patient before receiving the Boston keratoprosthesis Eye of a patient immediately following the Boston keratoprosthesis procedure Source: William Barry Lee, MD continued on page 58 Cornea editor's corner of the world

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