ROLE OF BLOOD COMPONENTS IN OCULAR SILICONE OIL EMULSIFICATION - STUDIES ON AN IN-VITRO MODEL

Purpose. To develop an in vitro model for silicone oil emulsification and to explore the blood components involved in this process. Methods, The capacity of various blood components to support silicone oil (100 0 CS) emulsification was studied by applying 0.5 mi oil on top of 0.5 mi saline containing various blood components. Each tube was sonicated for 150 seconds and centrifuged at 5000g for 20 minutes. Three phases were noted in the tube: At the top was clear silicone oil, in the mid dle was emulsified silicone oil, and at the bottom was aqueous solutio n. The tubes were photographed, and the percentage of the phase length containing emulsified silicone oil (middle) of the total length of th e three phases was calculated from the projected image of each tube. R esults, Emulsified silicone oil in plasma or serum was initiated after 100 seconds of sonication and quickly reached maximum (approximately 80%) at 120 seconds. The size of these oil droplets prepared in vitro was 0.0467 +/- 0.028 mm, closely resembling that observed in oil sampl es removed from a patient's anterior chamber (0.038 +/- 0.018 mm). Und er these conditions, silicone oil emulsified in the presence of whole blood cells occurred only at a concentration of 120 mu g protein/ml; i n the presence of red blood cell membranes, it occurred at a concentra tion of 60 mu g protein/ml. Lipoprotein-deficient serum failed to supp ort emulsification; however, samples of high-density lipoprotein and l ow-density lipoprotein supported this process. Purified high-density l ipoprotein-apolipoproteins supported oil emulsification. The addition of phosphatidylcholine further enhanced this process, but phosphatidyl choline alone failed to support emulsification. Conclusions. A simple and fast in vitro model to study factors affecting silicone oil emulsi fication was developed. Using this model, red blood cell membranes, pl asma lipoproteins, and purified HDL-apolipoproteins supported silicone oil emulsification. Lipids did not, but they had the capacity to enha nce the apolipoprotein-supported emulsification.