Abstract
Abstract: :
Purpose:There are clinical reports on so–called "sticky" silicone oil. This term describes the experience of difficulties to remove silicone oil, especially "heavy" silicone oil, used as an ocular endotamponade in cases of retinal detachment, from the vitreous cavity, at the end of the tamponade. To investigate the reasons for these difficulties in removal of silicone oil from the vitreous cavity due to adherence to the retina, explanted samples were analyzed and laboratory simulations were performed. Methods: Gas chromatography coupled mass spectroscopy of the headspace (GC/MS/HS) was used to detect volatile compounds in silicone oil samples explanted from patients qualitatively as well as quantitatively. Surface and interfacial tensions of the explanted samples were measured using the pendent drop technique. High–speed photography was used in the in vitro simulation. Results: In explanted samples of "heavy" silicone oil no significant differences in physico–chemical parameters like surface tension, concentration of additives and/or contaminants could be detected. There is a tendency of increased contamination with perfluorocarbon liquids in "sticky" samples. In explanted samples of conventional silicone oil polar impurities of a perfluorocarbon liquid could be detected in "sticky" samples only. Conclusions: In order to avoid "stickiness", ultrapurified substances have to be used as ocular endotamponades intraoperatively as well as postoperatively. Direct exchange between intraoperatively used fluorocarbon liquids and silicone oil has to be restricted to the absolutely necessary cases. When direct exchange seems to be mandatory, the exchange has to be performed as quickly and as careful as possible. Long contact times between both substances facilitate diffusion of fluorocarbon liquids into silicone oil, high pressure exchange creates turbulences which force dissolution of fluorocarbon liquids in silicone oil.
Keywords: retina • retinal adhesion • vitreous substitutes