[Corneal donation : Dilemma between growing demand and declining donor rate]. / Hornhautspende : Ein Dilemma zwischen wachsender Nachfrage und sinkender Spenderrate.

BACKGROUND: One of the most important requirements for successful corneal transplantation is the availability of donor tissue and thus the approval for postmortem corneal tissue donation. The aim of this study was to investigate donor willingness compared to the continuously increasing demand in recent years. MATERIAL AND METHODS: Archives of the local eye bank at the Department of Ophthalmology, University of Cologne, Germany in the time period between 1 July 2011 and 31 December 2015 were examined regarding the willingness for corneal donations in deceased patients from the University Hospital of Cologne. Absolute numbers of deceased, exclusion criteria for donation as well as the rate of negative and affirmative decisions were evaluated. RESULTS: In 235 (5.1 %) out of 4593 deceased at the University Hospital of Cologne, corneal donation was accomplished during the observation period. Of the patients 2923 (63.6 %) were excluded because of absolute contraindications for corneal donation and the rate of absolute contraindications increased from 46.6 % in 2011 to 68.9 % in 2015. Willingness for corneal donation in potentially suitable deceased patients diminished from 34.9 % in 2011, to 34.3 % in 2012, 35.5 % in 2013, 28.4 % in 2014 and to 24.1 % in 2015. In relation to the total number of deceased, the number of corneal tissue donations decreased from 11.5 % in 2011 to 3.5 % in 2015. CONCLUSION: Despite a rising demand, data from Cologne seem to indicate that the number of corneal donations has declined to some extent. In order to increase the number of corneal donors in the future, further educational work as well as standardization and optimization of the tissue donation process seem to be urgently needed.

[Influence of 20 % sulfur hexafluoride (SF6) on human corneal endothelial cells : An in vitro study]. / Einfluss von 20 % Schwefelhexafluorid (SF6) auf humane korneale Endothelzellen : Eine In-vitro-Studie.

BACKGROUND: In posterior lamellar keratoplasties, such as Descemet membrane endothelial keratoplasty (DMEK) and Descemet's stripping automated endothelial keratoplasty (DSAEK) an air bubble is left inside the anterior chamber to promote graft attachment during the early postoperative period. In the case of insufficient graft adhesion a renewed intracameral air injection is often necessary. The use of sulfur hexafluoride diluted with air (SF6 20 %) as an alternative to pure air may further enhance graft attachment and reduce the rebubbling rate. The effect of SF6 20 % on corneal endothelium is currently unclear and was therefore examined in vitro. MATERIAL AND METHODS: For this study 12 human corneoscleral discs were mounted in artificial anterior chambers, the systems were continuously filled with culture medium and the anterior chambers with air (n = 5) or SF6 20 % (n = 7) as tamponade. After 6 days of storage in the incubator endothelial cell density, toxicity on endothelial cells and corneal thickness were evaluated. RESULTS: There were no significant differences in endothelial cell loss (p = 1.000), endothelial cell count (p = 0.648), toxicity on endothelial cells (p = 0.048) and central corneal thickness (p = 0.905) between the two groups after 1 week. The level of significance was defined as p ≤ 0.05 and adjusted to p ≤ 0.0056 according to the Bonferroni correction for multiple testing. CONCLUSION: The use of SF6 20 % as tamponade in the anterior chamber for posterior lamellar keratoplasty can be proposed as a safe alternative to pure air filling related to endothelial cell loss. Increased toxic effects on the corneal endothelium by SF6 20 % were not detected in this study; however, further prospective clinical trials are needed to examine the long-term effects in humans.