[Efficient Use of Corneal Grafts through Multimodal Donor Tissue Splitting]. / Effiziente Verwendung von Hornhauttransplantaten durch multimodales Spendergewebesplitting.

BACKGROUND: The reduced availability of corneal donor tissue in Ukraine requires the most effective use of the available grafts. The present work describes and evaluates a method to obtain several small diameter corneal grafts from a single donor cornea ("multimodal donor tissue splitting"). MATERIAL AND METHODS: This retrospective cohort study includes keratoplasty procedures performed at the Department of Corneal Pathology, State Institution, "The Filatov Institute of Eye Diseases and Tissue Therapy of the National Academy of Medical Sciences of Ukraine", Odessa, Ukraine. The method of graft preparation includes either lamellar dissection of the entire graft or partial lamellar dissection to obtain two lamellar and/or full-thickness grafts. Grafts were not only cut in a circular manner, but the individual shape was also adjusted to match the shape of non-circular corneal defects. RESULTS: A total of 324 keratoplasties between January 2016 and December 2017, using 270 grafts, were included. In 54 cases (including 34 emergency situations), one transplant was used for two recipients. Of these, 43 were therapeutic keratoplasties and 11 peripheral lamellar keratoplasties due to grade III - IV recurrent pterygia. In two cases, two grafts for one patient were dissected from a single donor cornea. Out of 43 patients with curative keratoplasty, visual acuity improved in 28 eyes (65.1%) or remained unchanged in 15 eyes (34.9%). Postoperative visual acuity was dependent on the initial state of the eye, the localisation, the depth and the area of the corneal defect. In eyes with peripheral corneal localisation of ulcerations, even in the presence of corneal perforation, good functional results were obtained. CONCLUSION: If two or more grafts are obtained from a single donor cornea for different kinds of keratoplasty procedures, this reduces the need for corneal graft tissue and, consequently, the cost of preservation. Especially in regions with a high shortage of donor tissue, this provides additional tissue capacities for emergency situations.

[Emergency Keratoplasty with Porcine Xenografts in Necrotizing Keratitis]. / Notfallkeratoplastik mit porcinen Xenotransplantaten bei nekrotisierender Keratitis.

Background The great shortage of donor material in Ukraine makes it necessary to find additional sources of transplant material. A possible suitable material are the porcine corneas, as they are similar in structure and biomechanical parameters to the human cornea. The purpose of our study was to analyze the results of therapeutic keratoplasty (KP) with keratoxenotransplants from cryolyophilized porcine corneas in patients with severe necrotizing keratitis. Methods A retrospective analysis of 32 xenotransplantations patients with severe necrotizing keratitis (17 lamellar, 6 stepped perforating, 4 perforating, 5 "biological coverage" according to Puchkovskaya) was completed. Results All eyes could be preserved, but the graft was rejected in all eyes. A semitransparent xenograft (XG) was achieved in 9 patients (33.3%). The best results were obtained after lamellar XKP with an XT diameter of 3.5 - 6.5 mm. Lamellar XTs with larger diameters (7.0 - 10.0 mm) were opaque. Postoperatively, the intensity of the inflammatory response after stepped XKP was slightly lower than that of the classical perforating XKP. A new KP with human corneas had to be performed in 5 patients, in one case combined with an antiglaucomatous operation and in another case with cataract extraction. Antiglaucomatous surgery had to be performed in 5 patients (15.6%). Conclusion In the absence of human donor corneas, a porcine keratoxenoimplant can be used as temporary therapeutic keratoplasty in case of emergency stop the inflammation process and to save the eye. In cases of keratoxenoimplant, a poor visual outcome is expected.