EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
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44 EW ASCRS PREVIEW March 2013 April 19-23, 2013 Preserving corneal transplants by Rich Daly EyeWorld Contributing Writer Surgeons to provide insights on the new preventative steps specialists can use in corneal graft preparation, treatment, and implantation VISIONBLUE TM (TRYPAN BLUE OPHTHALMIC SOLUTION) BRIEF SUMMARY OF PRESCRIBING INFORMATION Indications and Usage VisionBlueTM is indicated for use as an aid in ophthalmic surgery by staining the anterior capsule of the lens. Contraindications VisionBlueTM is contraindicated when a non-hydrated (dry state), hydrophilic acrylic intraocular lens (IOL) is planned to be inserted into the eye because the dye may be absorbed by the IOL and stain the IOL. Precautions General: It is recommended that after injection all excess VisionBlueTM be immediately removed from the eye by thorough irrigation of the anterior chamber. Carcinogenesis, mutagenesis, impairment of fertility: Trypan blue is carcinogenic in rats. Wister/Lewis rats developed lymphomas after receiving subcutaneous injections of 1% trypan blue dosed at 50 mg/kg every other week for 52 weeks (total dose approximately 1,250,000-fold the maximum recommended human dose of 0.06 mg per injection in a 60 kg person, assuming total absorption). Trypan blue was mutagenic in the Ames test and caused DNA strand breaks in vitro. Pregnancy: Teratogenic Effects: Pregnancy Category C: Trypan blue is teratogenic in rats, mice, rabbits, hamsters, dogs, guinea pigs, pigs, and chickens. The majority of teratogenicity studies performed involve intravenous, intraperitoneal, or subcutaneous administration in the rat. The teratogenic dose is 50 mg/ kg as a single dose or 25 mg/kg/day during embryogenesis in the rat. These doses are approximately 50,000- and 25,000-fold the maximum recommended human dose of 0.06 mg per injection based in a 60 kg person, assuming that the whole dose is completely absorbed. Characteristic anomalies included neural tube, cardiovascular, vertebral, tail, and eye defects. Trypan blue also caused an increase in post-implantation mortality, and decreased fetal weight. In the monkey, trypan blue caused abortions with single or two daily doses of 50 mg/kg between 20th to 25th days of pregnancy, but no apparent increase in birth defects (approximately 50,000-fold maximum recommended human dose of 0.06 mg per injection, assuming total absorption). There are no adequate and well-controlled studies in pregnant women. Trypan blue should be given to a pregnant woman only if the potential benefit justifies the potential risk to the fetus. Nursing mothers: It is not known whether this drug is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when trypan blue is administered to a nursing woman. Pediatric use: The safety and effectiveness of trypan blue have been established in pediatric patients. Use of trypan blue is supported by evidence from an adequate and well-controlled study in pediatric patients. Geriatric use: No overall differences in safety and effectiveness have been observed between elderly and younger patients. Adverse Reactions Adverse reactions reported following use of VisionBlueTM include discoloration of high water content hydrogen intraocular lenses (see Contraindications) and inadvertent staining of the posterior lens capsule and vitreous face. Staining of the posterior lens capsule or staining of the vitreous face is generally self limited, lasting up to one week. Rx ONLY Revised: July 2005 Manufactured by: © Dutch Ophthalmic Research Center International b.v. Scheijdelveweg 2, 3214 VN Zuidland The Netherlands Distributed in the United States by: Dutch Ophthalmic USA 10 Continental Drive, Bldg 1 Exeter, NH 03833, U.S.A. Phone: 800-75-DUTCH or 603-778-6929 U.S. PAT. 6,367,480; 6,720,314 R ecent efforts to identify effective cornea transplantation techniques have progressed to identifying ways to preserve those transplants post-op. The relatively new session for cornea specialists at the ASCRS• ASOA Symposium & Congress will delve into the varying causes and responses to graft rejection and ways to pre-empt such tissue failures. "Corneal specialists have gotten pretty good at the different techniques for the various types of cornea transplants," said Christopher Rapuano, M.D., a moderator of the symposium "Objection to Rejection: Prevention and Management of Corneal Transplant Failure." Dr. Rapuano, professor of ophthalmology, Jefferson Medical College, Thomas Jefferson University, and director, cornea service, Wills Eye Institute, Philadelphia, and comoderator W. Barry Lee, M.D., will lead the discussion about which of the emerging variety of transplant options are better. "One of the important postoperative issues with many of these transplants is rejection," Dr. Rapuano said. "There have been new strategies over the years for managing rejection. We are doing more than ever to proactively decrease the risk of rejection." Among the issues addressed by the symposium's eight presentations and subsequent panel discussion are ways to move beyond just managing graft rejection to trying steps that decrease the risk and prevent rejection. For instance, Stephen C. Kaufman, M.D., will present a session titled "Calcineurin Inhibition to Prevent Corneal Graft Rejection." A key issue is whether Restasis (cyclosporine, Allergan, Irvine, Calif.), the only commercially available ocular calcineurin inhibitor, is too weak to function as an effective corneal graft rejection medication. But are stronger forms of cyclosporine, which is present in small amounts in Restasis and believed to help inhibit the activation of T-cells, acceptable to use? Perhaps other calcineurin inhibitors may prove more effective, Dr. Rapuano said. Friedrich E. Kruse, M.D., is planning a presentation on "Is less more? Rejection in Endothelial Keratoplasty (DMEK Versus DSAEK)." This presentation will explore the theory that Descemet's membrane endothelial keratoplasty causes less rejection than Descemet's stripping endothelial keratoplasty. "One idea is if there is less tissue being transplanted, there are fewer antigens, less antigenic load, and that induces less rejection," Dr. Rapuano said. "Not that the rejection rate for DSEK is high." The rejection rates for DSEK range from about 5% to 10%, while DMEK's rejection rates are less than 5%, he said. "Anything that decreases rejection is good," Dr. Rapuano said. Also examining transplant rejection specifics is "Rejection With DALK: Is It a Concern?" by Vincent Borderie, M.D. "The answer is that there is no concern for endothelial rejection, which is the very back layer of cells," Dr. Rapuano said. "That is the most important form of rejection." However, deep anterior lamellar keratoplasty can result in either stromal rejection or epithelial rejection, which are both usually less serious and less debilitating. But both types of rejection can cause problems, including corneal scarring, corneal opacities, and decreased vision. "The bottom line is it should be a concern but less of a concern," he said. "Anti-Angiogenesis Therapy: Corneal Graft Rejection Implications" by Reza Dana, M.D., will examine the preservation of transplants through blood vessel management. This approach is based on the fact that the risk of corneal graft failure increases with the number of corneal blood vessels. Understanding the surgical options in cases of a failed graft will be the focus of a session by Bruce D. Allan, M.D. The reasons behind that graft failure can help determine the clinician's options, said Dr. Rapuano. For instance, if a PK failed due to the cells on the back layer failing, then a DSEK or a DMEK might be a good option. However, transplant failures due to high astigmatism might improve if the transplant is resutured. Alternatively, failures due to poor ocular surfaces might require a keratoprosthesis. "Graft Failure in Glaucoma Drainage Devices: Causes and Options for Treatment" is the title of a session by David C. Ritterband, M.D. This talk will address issues around glaucoma's impact on graft continued on page 45