Eyeworld

EW CORNEA 22 January 2011 by Matt Young EyeWorld Contributing Editor Accurate cornea identification E ye bank corneas are often misidentified as having previously had LASIK when in fact they have not, according to new re- search. "There is approximately a 10% rate of misidentified post-LASIK corneas in eye banks," according to study co-author Hans E. Gross- niklaus, M.D., LF Montgomery Ophthalmic Pathology Laboratory, department of ophthalmology, Emory Eye Center, Atlanta. This is a serious issue, the au- thors contend, because it has impli- cations for the availability of corneal tissue. "The growing popularity of refractive surgery poses a potential problem of future availability of quality tissue for corneal surgery," Dr. Grossniklaus reported. "Current Eye Bank Association of America standards do not allow the use of tis- sue with previous corneal surgery for penetrating keratoplasty." The implication is that many corneas are deemed unsuitable for transplantation surgery on the basis that they have undergone LASIK when in fact, they haven't. Misiden- tifying corneas also has other serious consequences for resulting quality of vision according to the research, published in the June 2010 issue of Cornea. "Misidentified post-LASIK corneas result in mean loss of poten- tial donor corneas, and the failure to identify corneas with prior refractive surgery increases the risk of uncer- tainty of refractive outcome and de- creases the structural integrity of donor material," Dr. Grossniklaus re- ported. Properly identified—finally Dr. Grossniklaus analyzed 161 eye bank corneas deemed to have had LASIK, of which 155 had informa- tion regarding the decision that LASIK was carried out. The corneas were placed into three groups ac- cording to how the decision that they underwent LASIK was made. Group 1's decision was based upon patient history only, and 74 corneas were in this group. Group 2's deci- sion was based upon slitlamp exami- nation only, and 22 corneas were in this group. Group 3 (59 corneas) had both a patient history and slitlamp examination performed. Dr. Grossniklaus then performed a histopathologic diagnosis of prior LASIK on all the corneas. "Histopathologic examination re- vealed that 16 donor eyes (10.3%) had no evidence of prior LASIK sur- gery," Dr. Grossniklaus reported. "The rate of misidentified corneas as having previous LASIK was 13.5% in the history only group (10 of 74) and 18.2% in the slit-lamp examina- tion only group (4 of 22). In eyes with both history and slit-lamp ex- Folded donor cornea being inserted; it becomes vital that all donor corneas having undergone LASIK are adequately labeled Source: Mark Gorovoy, M.D. Donor cornea post-DSAEK Source: Mark Gorovoy, M.D. What to expect when transitioning from PK to DSEK W ith careful attention to detail, Descemet's stripping endothelial keratoplasty (DSEK) is a safer, more effective, and overall supe- rior treatment for corneal endothelial disease than penetrating keratoplasty (PK), according to a case study by Eydis Olafsdottir, M.D., ophthalmology department, University of Iceland, Reykjavik, Iceland. Dr. Olafsdottir reported his experiences during the transition from PK to DSEK between April 2008 and April 2009. The case study, which was published in Acta Ophthalmologica (DOI: 10.1111/j.1755- 3768.2010.02011.x), followed 11 eyes of 11 patients, five men and six women, with a mean age of 78. All eyes were pseudophakic at the time of the DSEK operation and were made pseudophakic by having cataract sur- gery one month prior to the DSEK surgery. In the first two surgeries, forceps were used to introduce the graft into the anterior chamber. Dr. Olafsdottir found that forceps insertion threat- ened to cause more intraoperative trauma to the endothelium of the donor disk and instead used the Busin glide for the other nine operations. All grafts were attached and clear at both the six and 12-month fol- low-up exams. One case of graft rejection occurred, and that was a year after surgery and one month after topical steroids were discontinued. The rejection was successfully treated with topical steroids and remained clear, according to the case study. Dr. Olafsdottir found that DSEK "has several advantages over PK—in- cluding early visual recovery, better refractive stability and postoperative refractive outcomes, less wound and suture-related complications, and less intraoperative and late choroidal hemorrhage risk," the study said. "However, the DSEK procedure itself is more complex, possibly affecting the results of the surgeon's learning curve." Dr. Olafsdottir cited a few key elements for successful DSEK surgery, including inserting the donor tissue without damaging the endothelium, getting the donor tissue to adhere, and achieving long-term survival of the graft. "This can be difficult for the novice surgeon, but choosing adequate surgical techniques and tools are of great help," he wrote.

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