EyeWorld Asia-Pacific June 2015 Issue

28 Corneal lamellar surgical procedures June 2015 EWAP SECONDARY FEATURE Views from Asia-Pacific Gerard SUTTON, MBBS(UNSW), MD(AUCK), FRANZCO Vision Eye Institute, Chatswood 270 Victoria Ave., Chatswood, NSW, Australia Tel. no. +02 9424 9999 gerard.sutton@visioneyeinstitute.com.au T here is no doubt that we are experiencing the most significant and rapid evolution of corneal transplantation techniques in history. It has been an exciting time to be a corneal transplant surgeon and the ride has not finished yet. Endokeratoplasty in all its iterations is an aesthetically pleasing intuitive technique. Ultrathin DSAEK is my current procedure of choice although I am moving to DMEK because of the reported advantages of reduced graft rejection. It is true that issues of ocular surface disease, astigmatism, and suture complications are avoided and the visual results are good. However, the evidence that graft survival is better is not supported by the literature and certainly not by the Australian Corneal Graft Registry (ACGR) which offers arguably the most rigorous test of new corneal transplant procedures. If graft survival was the key criteria in choosing the appropriate procedure we would all still be doing penetrating keratoplasty. To suggest that penetrating keratoplasty should not be used for endothelial-only disease therefore ignores this important fact. DALK is my preferred choice of surgical procedure for keratoconus but again the ACGR suggests that if graft survival was our KPI we would only be doing penetrating keratoplasties. Other studies, however (Tan et al. Br J Ophthalmol . 2010 Oct;94(10):1295-9), suggest that aerodissection DALK techniques are superior visually and in terms of graft survival. It is important to note that in patients at risk of vascularization, a DALK can result in interface blood vessels that are difficult to manage. Finally, in many areas of the Asia-Pacific, and I have worked for over 10 years in Myanmar, the indication for corneal surgery (infection, perforation) mandate full thickness transplantation. To suggest that penetrating keratoplasty in this context is redundant is manifestly false. The future, however, may reveal a completely different outcome altogether. Kinoshita, Koizuimi, and colleagues in Kyoto are pioneering endothelial injection with ROCK inhibitors for endothelial failure. If this technology continues to evolve, all forms of endokeratoplasty will be historical. If all patients with progressive keratoconus had collagen crosslinking there would be little need for DALK. In this scenario, corneal surgeons would become an endangered species. Of course, those patients with full-thickness disease would still require—yes, you guessed it—a penetrating keratoplasty. It’s not time to hand in our PKP skills just yet. Editors’ note: Dr. Sutton declared no relevant financial interests. LIM Li, MD Senior Consultant, Co-Head (Clinical & Education), Corneal and External Eye Disease Service Singapore National Eye Centre 11 Third Hospital Avenue, Singapore Tel. no. +652277255 lim.li@snec.com.sg T he first penetrating keratoplasty was performed by Eduard Zirm in 1905 and PK has since been the dominant transplant procedure for more than half a century. Most types of corneal blindness can be successfully treated with this procedure. However, complications such as graft rejection, high post-graft astigmatism and traumatic post corneal graft wound dehiscence can significantly affect visual outcome. In recent years, newer forms of lamellar keratoplasty which selectively replace only the diseased layers of the cornea have been introduced to improve visual outcomes. Endothelial keratoplasty, which selectively replaces the diseased corneal endothelium in conditions such as bullous keratopathy and Fuchs’ dystrophy, has resulted in more rapid visual recovery and by retaining the host corneal stroma has eliminated complications such as graft astigmatism and traumatic graft wound dehiscence. Deep anterior lamellar keratoplasty is being performed for stromal diseases such as keratoconus and by retaining the host endothelium has eliminated the endothelial rejection risk. Penetrating keratoplasty still plays a role in cases that are not amenable to lamellar procedures. About 400 corneal transplantation procedures were performed at the Singapore National Eye Centre last year and about a quarter of these procedures were penetrating keratoplasty procedures; about half were endothelial keratoplasty procedures and the remaining quarter were anterior keratoplasty procedures. Penetrating keratoplasty was performed in cases with full-thickness corneal involvement and for tectonic and therapeutic indications. These conditions included full-thickness corneal scars, long-standing bullous keratopathy with significant corneal stromal scarring, severe infective keratitis (figures 1 and 2) and large corneal perforations. Editors’ note: Dr. Lim is a consultant for Allergan (Irvine, Calif.) but has no financial interests related to her comments. Figure 1. Severe full-thickness Fusarium keratitis with hypopyon Figure 2. Therapeutic penetrating keratoplasty performed – clear graft at 1 year Source (all): Lim Li, MD Penetrating - from page 26