Is tisseel a viable option in posterior lamellar keratoplasty?

PURPOSE: It is well known that Tisseel Fibrin Sealant provides an excellent tissue adhesive. However, its thick and viscuous nature makes it nearly impossible to apply it in a uniform and thin layer. We propose applying the sealant phase as a dry powder and polymerizing it in-vivo by exposing it to thrombin solution after a graft has been placed. METHODS: For each experiment two rabbit corneal buttons were affixed to each other using either Tisseel or thrombin plus dry fibrinogen component, the tensile strength of the bond was then tested in the tension box. Balanced salt solution was used as an aqueous substitute. RESULTS: Tisseel was demonstrated to create significant adhesive tensile force (expressed as N/m) between corneal buttons (P < 10). Using only the dry fibrinogen component followed by injection of the thrombin solution directly into the balanced salt solution did not significantly alter the strength of the bond (P = 0.18). CONCLUSION: The use of the dry fibrinogen component followed by injection of thrombin solution into the balanced salt solution, without the accompanying fibrinolysis inhibitor, is equally effective in adhesive strength when compared to complete Tisseel. This technique may be used in lamellar corneal surgery, although there would be potential difficulties with its application in the in vivo setting.

Prophylactic gatifloxacin therapy in prevention of bacterial keratitis in a rabbit laser in situ keratomileusis model.

PURPOSE: Use the ID(50) (infectious dose to 50% of experimental animals) to quantify the most effective prophylactic dosing regimen to use with gatifloxacin 0.3% (Zymar) for the prevention of keratitis in a rabbit laser in situ keratomileusis model of Staphylococcus epidermidis infection. SETTING: University Laboratory, University of Arizona, Tucson, Arizona, USA. METHODS: Two groups of rabbits were compared in each of 2 experiments that were separated by 12 months. In the first experiment, rabbits receiving no postoperative antibiotic therapy (Group 1) were compared with rabbits receiving postoperative antibiotic therapy (Group 2). In the second experiment, postoperative antibiotic therapy (Group 3) was compared with preoperative and postoperative antibiotic therapy (Group 4). All antibiotic regimens used gatifloxacin 0.3%. Before antibiotic therapy began, corneal pockets were created in the right eye of each rabbit and all rabbits received balanced salt solution (BSS) only or BSS and S epidermidis inoculations in the corneal pocket. Rabbits were monitored for corneal infiltrates after surgery. RESULTS: The ID(50) of the first, second, third, and fourth groups of rabbits was 10(2), 10(4), 10(5), and 10(7) organisms, respectively. The data showed a statistically significant difference between rabbits receiving BSS only and most rabbits receiving BSS plus inoculate at each postoperative measurement (P<.05). CONCLUSIONS: The findings suggest that the use of both preoperative and postoperative antibiotic therapy may be most effective in preventing infection. Postoperative antibiotic therapy increased the number of S epidermidis necessary to cause infection by at least 100-fold over no antibiotic intervention. Preoperative plus postoperative antibiotic therapy increased the number of bacteria necessary to cause infection by at least 100-fold over postoperative therapy alone and by more than 10000-fold over no antibiotic intervention.