EyeWorld Asia-Pacific September 2012 Issue

September 2012 8 EWAP FEAturE Managing post-keratoplasty vision by Vanessa Caceres EyeWorld Contributing Editor AT A GLANCE • Refractive surgery after keratoplasty has a number of challenges, including astigmatism, stability of the refractive error, possible rejection, and difficulty cutting the flap • Refractive options include PRK with MMC, LASIK, phakic IOLs, and AK • Use of a femtosecond laser can assist with refractive treatment, particularly for laser-assisted AK • Future treatment options will include more frequent use of the laser, corneal crosslinking prior to surgery, and further development of phakic IOLs An intraoperative image on the LenSx. The red circle points to the 6 o’clock ink marking placed on the slit lamp just prior to surgery. This technology gives the option to rotate the AK axis until it meets the marking, avoiding cyclorotation errors. Right: Pentacam comparison shows the pre-op high cylinder (left), the post-op cylinder following the femtosecond AKs (middle), and the difference (right). These topographies are from the same case shown on the left intraoperative image. It is noteworthy that the difference map is identical to the pre-op, underlining the accuracy of this approach. An intraoperative LenSx image demonstrating the final adjustment of AK depth guided by the intraoperative OCT image obtained. Left: Intraoperative image shows preparation of two AK femtosecond incisions. Right: The same case seen a few minutes later by slit lamp. Seasoned surgeons share old and new refractive techniques R efractive surgery in post- keratoplasty patients has a host of challenges associated with it. However, with the right techniques and tools, it does not have to be as difficult as you might initially think. First, let’s talk about the challenges. “Cutting a flap is more challenging because of the donor-host interface,” said John Berdahl, MD, Sioux Falls, SD, USA. “This may be one of the few situations where a microkeratome is preferred. Using a double pass with a femtosecond laser can also be performed.” Astigmatism is also a challenge, said John Kanellopoulos, MD, associate clinical professor of ophthalmology, New York University, New York, NY, USA, and director of Laser Vision, GR Institute, Athens, Greece. “It appears that the astigmatism hurdle is persistent, even in an era where femtosecond lasers have held some promise to reduce post-penetrating keratoplasty [PK] astigmatism,” he said. In some cases, particularly with keratoconus, high astigmatism can be associated with a partial wound dehiscence, increasing the curvature at the graft-host interface, Dr. Kanellopoulos said. “This challenge needs to be identified by the clinician because obviously refractive surgery in these specific cases would not necessarily help in visual rehabilitation and may even worsen the situation,” he said. Use of anterior segment optical coherence tomography (OCT) or Scheimpflug imagery can help surgeons better evaluate the graft- host interface, Dr. Kanellopoulos said. Rejection, re-epithelialization, and cataract formation inducing the refractive error are other challenges associated with a prior keratoplasty, Dr. Berdahl said. Surgical approaches Surgeons have a few options in their arsenal to treat post- keratoplasty patients. “The magic potion for us has been PRK with mitomycin-C [MMC],” said Richard L. Lindstrom, MD, adjunct professor emeritus, ophthalmology department, University of Minnesota, Minneapolis, Minn., USA, and founder, Minnesota Eye Consultants, Minneapolis. He uses MMC for 1-2 minutes followed by a thorough rinse in his post- keratoplasty patients. This contrasts with only 12 seconds of MMC in most PRK patients who have not had a previous keratoplasty. Dr. Lindstrom has used LASIK before in keratoplasty patients but has found better results with his current approach. However, without MMC, he noticed the patients got a good deal of corneal haze. “The surface ablation approach seems to give a better outcome for us,” he said. “You get some smoothing and higher order Rotating on 6 o’clock maRk adjusting thickness/depth 7mm oZ 60 degRees X 2 The precision of axis of the AKs are evaluated. The cobalt blue illuminated image on the left highlights the fluorescein-stained incision gutters. The slit is rotated in the middle image to match the axis of the incisions. In the right image, the exact axis is noted on the slit lamp goniometer to match the planned steep axis of 153 degrees. Source: A. John Kanellopoulos, MD pRecision: lensX ak aXis