Purpose
To examine the feasibility of a novel technique for plaque radiotherapy placement and removal, using fibrin glue and urokinase, respectively, to explore quantitative variables, and compare these to conventional suturing.
Methods
The feasibility of the surgical technique was tested in 6 enucleated porcine eyes. Plaques without radioactive seeds were placed on the sclera beneath the conjunctiva, fibrin glue was then applied on the plaque, covering it and its immediate environment (Figure 1A). The eyes were then submerged in plasma for 3 days. Thereafter, attempts were made to dissolve the glue and release the plaque using urokinase (10,000 units/10cc normal saline (NS)) or NS only, by a surgeon masked as to the nature of the dissolving fluid (Figure 1B). In a second group of eyes, adhesion strength was measured using a system constructed of a tension transducer, a pulley, a transmission wire and an electrical winch (Figure 2). The eyes were prepared as described above, after which they were submerged in plasma for 5 days (replaced every 36 hours). Measurements were performed subsequently on 5 glued eyes and 5 eyes in which the plaques were sutured, and the results were recorded and analyzed.
Results
One to 2 ml of fibrin glue was used in order to fix each plaque in place. In all cases the urokinase syringe was identified, as the NS had no effect on the plaque-glue-eye complex, whereas the urokinase dissolved the adhesion between the glue layer and surrounding tissues. The plaques were then delivered out easily, after which a glue "blanket" was removed in full. No tissue defects were observed thereafter. The volume of urokinase used per eye was 0.38±0.08 ml. In the second part, the weights needed to detach the plaques were 0.35±0.17 kg and 0.41±0.08 kg for the glue and sutures, respectively (P=0.59).
Conclusions
A novel biological adhesive and dissolvent system using fibrin glue and urokinase was found to be a feasible technique for plaque surgery in an ex-vivo animal model. Fibrin glue was as durable as sutures, but may be preferable to the use of sutures in enabling precise plaque positioning and in the lack of complications, such as globe perforation or plaque displacement. Further in-vivo experiments are warranted.