EyeWorld Asia-Pacific June 2011 Issue

June 2011 13 EW FEATURE For patients with Fuchs’ dystrophy and cataracts, combined phaco and DSEK might be beneficial Source: Ricardo Amin, MD outcomes.” On the flip side of the coin, however, he finds that for the beginning surgeon, doing the procedure in stages is probably easier. “When you do the cataract surgery first and you wait for a month or more, the lens implant has time to fibrose or basically become fixated in the capsule,” he said. “The capsule shrink wraps around the lens implant; it tightens itself with the zonules, so when you go to put your graft in, you’re less likely to dislodge the implant.” Dr. Price finds that the whole diaphragm of the lens capsule is stiffer after being in place for a while. “It moves some but not as much as when you do a combined cataract procedure,” he said. “When you put air in an eye that you’ve done a cataract procedure on at the same time, the implant goes back posterior quite a bit more than it does if it has been a month or two out.” With the combined procedure there is more give to the zonules because the capsule hasn’t shrunk down at that point. Blue ribbon technique Effectively performing the procedure involves a few different steps, Dr. Holland finds. “At the outset of the procedure surgeons have to figure out what size DSEK they want to do—typically it’s in the 8- to 9-mm range,” he said. “They measure the cornea and estimate the size, so that’s an extra step.” In addition to the standard cataract paracentesis, Dr. Holland makes another one. “I like at least two to manipulate the EK button,” he said. The only other extra step is to make a 4.5-mm incision instead of a typical 2.2- to 2.4-mm incision for standard phacoemulsification. Dr. Holland marks the 4.5-mm length but initially performs the phacoemulsification procedure through the typical 2.2-mm incision. “We take the cataract out, put the lens implant in, and before we open the wound we strip Descemet’s,” he said. “That’s still done under a floored incision.” Under viscoelastic he would then score Descemet’s. “We like to do a descemetorhexis, where we start the tear of Descemet’s membrane and then tear it as we do with a capsulorhexis,” he said. “This prevents the peripheral tear of Descemet’s beyond the size of the DSEK button.” After stripping the Descemet’s membrane, Dr. Holland removes all of the viscoelastic and then opens the incision to the desired 4.5- or 5-mm length. “We insert our DSEK button, close the wound, and establish the amount of air in the anterior chamber that we want,” he said. “There are different techniques, but most surgeons will overfill the anterior chamber for the first few minutes and then after 5 or 10 minutes let some of the anterior chamber air out so they don’t get a pupillary blockage during the postoperative period.” With the cataract portion of the procedure, Dr. Price stressed that it’s important to use a cohesive rather than a dispersive viscoelastic. “The reason is once you remove the cataract, you want to strip Descemet’s in the central part of the cornea and put your DSEK graft up,” he said. “If there’s a dispersive viscoelastic then it’s difficult to ensure that you’ve gotten all of the viscoelastic out.” Determining the correct IOL power to use can also be tricky. “There are series that have been reported that show hyperopic shifts after DSEK of anywhere from .5 D to 2 D,” Dr. Price said. He finds that some of the hyperopic shift is dependent on how thick the donor tissue is and on the shape or contour of the button. “Just like everyone is a different height and weight, corneas come in different shapes and contours,” he said. “When you cut with a microkeratome, you may have some that have more of a meniscus shape and others that are more planar.” For those that are more meniscus- shaped and thicker on the edge, this may ultimately result in a greater hyperopic shift. To help overcome problems with hyperopic shift, Dr. Holland recommended developing a nomogram of sorts. “Surgeons should look at their results, but typically the EK procedure causes a hyperopic shift,” he said. “The fudge factor is somewhere in the range of –.75 to 1.50 D that you would put into your preoperative calculation—for us it’s between 1 D and 1.25 D.” Prized outcomes It is the DSEK portion of the combination procedure that ultimately tends to be the limiting factor for outcomes. To get the best outcomes with the combination technique, Dr. Holland recommended using the thinnest tissue with a process he terms “thin EK.” He defined those patients as ones who receive eye bank tissue of 130 microns or less. The thin EK technique evolved over the last few years. In almost all cases, eye banks precut tissue. “It used to be that the average thickness N. Venkatesh PRAJNA, MD Chief, Cornea and Refractive Surgery, Aravind Eye Hospital No. 1, Anna Nagar, Madurai, India 625 020 Tel. no. 0452-4356100 Fax no. 0452-2530984 prajna@aravind.org The evolution of DSEK has revolutionized visual rehabilitation for patients with endothelial disorders like Fuchs’ dystrophy. This article discusses the potential advantages and disadvantages of combining DSEK with cataract surgery in patients with coexistent Fuchs’ dystrophy and cataract. Before we contemplate any surgical option, however advanced it may be, it is very important to assess the occupational and functional needs of the individual patient. It has to be understood that the mere presence of corneal guttata changes and cataract alone is not an indication for any surgery. In fact, some of the patients with early to moderate Fuchs’ dystrophy and nuclear sclerosis are quite comfortable with spectacle-aided visual acuity. I completely agree with Dr.Holland, that in cases with corneal guttata, where there is no corneal edema, it may be wiser to do cataract surgery alone. It has been our experience that such patients are quite pleased with the results of cataract surgery alone. The presence of corneal edema is an indication for contemplating DSEK and, in such instances, it would be prudent to combine DSEK with phacoemulsification, even if the cataract changes are mild. The advantage of such an approach is that it would be a single straightforward surgical option with quicker visual rehabilitation. In sequential surgery, the risk of further endothelial loss and possible dislocation of the corneal button is significant. It is also important to remember that DSEK carries the same risk for graft rejection and hence the decision to perform DSEK should not be taken lightly. The mere presence of corneal guttata alone should not be an indication for doing DSEK. Hence, in conclusion, the treatment should be customized towards each and every patient. Editors’ note: Dr. Prajna has no financial interests related to his comments. Views from Asia-Pacific continued on page 14