EyeWorld Asia-Pacific September 2018 Issue

52 EWAP CORNEA September 2018 Graft 4 months out illustrating stromal rejection (20% of cases in DALK) Femto DALK host dissection Source: Bruce Allan, MD by Stefanie Petrou Binder, MD EyeWorld Contributing Writer Grafting in keratoconus A corneal grafting specialist looks at short and long-term outcomes with PK and DALK E arly graft survival in deep anterior la- mellar keratoplasty (DALK) for keratoco- nus patients is improving thanks to a number of smart variations in the technique that have been developed over time. Giving the keynote lecture at the 22nd ESCRS Winter Meeting, Bruce Allan, MD , Moorfields Hospital, London, UK, discussed why penetrating keratoplasty (PK) is losing some ground to this emerging tech- nique. “There is an ongoing debate regarding grafting for keratoco- nus. On the one hand, your head is telling you to use and keep the endothelium. But then the registry studies are telling us something different,” Dr. Allan said. “Why is it that our head is telling us to use DALK? Because it avoids the endothelial rejection and acceler- ated endothelial cell loss that are seen in PK.” Accelerated endothelial cell loss following PK is well docu- mented in the literature. A system- atic review based on 11 published studies revealed accelerated endothelial cell loss in eyes treated with PK versus DALK. It showed that DALK was not associated with endothelial immune graft rejection, which the investiga- tors thought could simplify the long-term management of these eyes compared with PK. The study also demonstrated that DALK was equivalent to PK for CDVA. 1 Dr. Al- lan noted that while DALK could cause accelerated endothelial cell loss for up to 6 months after sur- gery, the rate of cell loss dramati- cally dropped after 6 months. These data, however, address outcomes in the short term. Know- ing more about the long-term course of corneal graft surgery is decisive. Registry evidence that included 4,834 eyes suggested that PK performed in eyes with kera- toconus had a first graft survival rate of 17% at 23 years post-graft, indicating that young patients were likely to need at least one repeat graft during their lifetime. 2 For first grafts, the 10-year survival was 89%, the 20-year survival 49%, and the 23-year survival was 17%. The 10-year survival of a sec- ond graft was 53%, and for third grafts, it was 33%. 3 “The Australian registry stud- ies are the most important piece of research in corneal medicine in the last 50 years,” Dr. Allan said. “They guide everything we tell our patients in terms of prognosis and outcomes. They show us that be- tween 20 and 30 years, most grafts run out of endothelial power. There is an accelerated failure in that time period for first grafts. Survival of second and third grafts is worse still. We usually graft keratoconus patients in their 20s, quite early in life, which is why a procedure with long life is what we are striving for.” Long-term graft survival for the duration of a patient’s life- time was predicted with DALK, according to a study that used a joint regression model to describe long-term graft survival, involving 142 consecutive DALK surgeries and 142 matched PKs. The inves- tigators predicted a median DALK graft survival of 47 years and a median PK graft survival of 17 years. 4 While DALK grafts that “take” survive a long time, how many grafts actually “take” in the first place? Researchers found that early