EyeWorld Asia-Pacific June 2014 Issue

54 EWAP CORNEA June 2014 Eye on optical changes post-DSAEK by Maxine Lipner EyeWorld Senior Contributing Writer Considering the matter of scatter E ndothelial keratoplasty passed penetrating keratoplasty (PK) in popularity in 2012 for procedures used for corneal transplantation, according to Holly B. Hindman, MD , Flaum Eye Institute, University of Rochester, Rochester, NY, U.S. Eye Bank Association of America statistics in 2012 showed that 23,049 corneas were used for For eyes that have undergone DSAEK such as this one, study results indicate it is a decrease in light scatter, not in higher order aberrations, that accounts for visual improvements in the first year postoperatively. Source: Holly B. Hindman, MD endothelial keratoplasty in the U.S. and 21,422 were used for PK, she reported. With this burgeoning popularity, more attention is being focused on attaining the best outcomes. New study results published in the December 13, 2013 issue of Cornea indicate that with Descemet’s stripping automated endothelial keratoplasty (DSAEK), it is a decrease in light scatter, not higher order aberrations, that can account for visual improvement in the first year postoperatively. When the endothelial keratoplasty procedure was first emerging a few years back, Dr. Hindman’s interest was piqued as to why patients weren’t getting back to the same level of acuity with deep lamellar endothelial keratoplasty (DLEK) as they were with penetrating keratoplasty. “It wasn’t major, but early reports were showing vision of about 20/40 for DLEK, whereas the penetrating keratoplasty patients were achieving better visual acuities,” Dr. Hindman said. In her view, there were a couple of possible reasons for this. If the retina and optic nerve are intact and the neural pathways are good, Dr. Hindman pointed out, the two main corneal findings that can hinder visual acuity are scatter and distortion. “When you’re driving and there is a lot of salt on the windshield, you have the type of effect that is scatter,” Dr. Hindman said. “But you can also get distortion, which is aberration.” She described such distortion as akin to looking in a fun house mirror. “With endothelial keratoplasty, we’re leaving the bulk of the host cornea intact and putting the donor tissue onto the back, which changes the posterior corneal profile thereby changing the pathway the light has to travel to get through the eye,” she said. “There’s also the creation of a donor host stromal interface, which in addition to anterior host stromal changes associated with chronic edema is another source of scatter.” Dissecting DSAEK With this in mind, Dr. Hindman and fellow investigators launched the study to determine how these factors changed with time. In particular, investigators wanted to determine how vision was affected by these factors in DSAEK cases. “We studied ocular aberrations rather than corneal aberrations so that we