Dr Alvin Young, Council member, HKST. (Chief of Service & NTEC Cluster Coordinator (O&VS), Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong).
Corneal transplantation has come a long way since the first successful human surgery performed more than 100 years ago in 1905. Over the past decade, advancements in microsurgical equipment and refinements in grafting techniques have led to the development of novel forms of anterior and posterior (endothelial) lamellar keratoplasty, replacing only the diseased tissue instead of the entire thickness of the cornea ( Hong Kong Med J. 2012 Dec;18(6):509-16 ). The number of lamellar (LK) procedures performed in HK has been steadily growing from 25 cases in 2008 to 77 cases in 2012. Unfortunately, the number of cornea harvested and subsequently distributed for transplant in 2002 was 281, and in 2012 was only 255, reflecting the local problem of poor organ donation rates.
The common indications of anterior transplant would include non full thickness corneal scars, dystrophy and or keratoconus. On the other hand, for posterior or endothelial keratoplasty, the main indications would be primary endothelial failure related to dystrophy, or secondary to prior trauma (including surgery and or laser) and or inflammation.
The big surge in LK is mainly related to the growth in numbers of endothelial keratoplasty (EK) performed. The current hot issue on EK is whether one should transplant only an extremely thin donor tissue (DMEK), with the potential to offer better visual acuity and even less chance of rejection ( Ophthalmology. 2012 Mar;119(3):536-40. doi: 10.1016/j.ophtha.2011.09.019 ). However, there is a relative high tissue wastage rate that must be considered, especially in the local context of graft scarcity. ( Clin Experiment Ophthalmol. 2008 Nov;36(8):707-8. doi: 10.1111/j.1442-9071.2008.01883.x. )
The eye donor selection criteria of the HA Eyebank has been updated and aligned with international standards since Feb 2013. The main difference is the inclusion of deceased cancer patients as eligible CORNEAL donors, provided that they did not have lymphoma, leukaemia, myeloma and malignant tumours of ocular or peri-ocular area. This may help to alleviate the shortage of cornea for HK.
(I wish to thank Ms Catherine Wong and eye bank staff in their kind assistance of local data)