The influence of explants on the physical efficiency of tamponade agents

Background: The effectiveness of tamponade agents depends on the interfacial energies of the surfaces involved, the buoyancy of the tamponade agent and its volume. The ability of gas or silicone oil to tamponade retinal breaks may also depend on the shape of the vitreous cavity, and this in turn may be altered by the application of surgical explants or encircling bands. Method: We have constructed a model eye chamber (using surface-modified polymethylmethacrylate) to study the influence of indentations on the overall tamponade effect. Results: We show that in the case of silicone oil, the presence of indentations may enhance the tamponade to specific areas of the model eye cavity, namely inferiorly and posteriorly, and may diminish the tamponade to areas immediately adjacent to the indentations. This modification of the tamponade effect is not observed when air is used. Conclusion: The position of explants is critical to the efficiency of tamponade agents.