Emulsification of silicone oils with specific physicochemical characteristics

Abstract

To determine the exact role of various factors in silicone-oil emulsification, we investigated eight different silicone oils with specific physicochemical characteristics in terms of their rate of emulsification. The silicone oils were defined by viscosity, volatility, amount of low-molecular components, electrical resistivity, degree of purification and chemical composition. The viscosities differed between the ranges of 1000 and 10,000 cs. The silicone oils included purified polydimethylsiloxane (PDMS), hydroxyl-enriched PDMS and trimethylsiloxy-terminated polydiphenylsiloxane (PDPS). As emulsifiers we used 0.1% solutions of fibrinogen, fibrin, gamma globulins, acidic alpha-1-glycoprotein, very-low-density lipoprotein and serum dissolved in sterile, distilled water as well as in balanced salt solution. The group of low-viscosity silicone oils (1000 cs) was least stable. The greatest difference in stability was found among purified PDMS, having viscosities between 1000 and 5000 cs. The most stable oil was purified PDMS, whose emulsification rate was almost identical at 5000 and 10,000 cs. High contents of hydroxyl end groups enhanced silicone-oil emulsification to a greater extent than did phenyl side groups. The strongest emulsifiers were fibrinogen, fibrin and serum, followed by gamma globulins, very-low-density lipoprotein and acidic alpha-1-glycoprotein. Balanced salt solution accelerated silicone oil emulsification in all cases. For reduction of emulsification in vivo, purified PDMS of high viscosity should be used. Biologically active emulsifiers found in hemorrhages or inflammatory situations might be lowered in vivo by hemostasis and sufficient postoperative anti-inflammatory therapy.

A new heavy internal tamponade in vitreoretinal surgery: an in vitro study

“…These substances may reduce the interfacial tension and greatly facilitate the emulsification. [51][52][53][54] A recent study by Dresp and Menz 55 demonstrated a great variety of contaminants in emulsified samples of explanted silicone oil, when compared with nonemulsified samples. This was found in both 1000 and 5000 cs samples.…”

Experimental retinal tolerance to very low viscosity silicone oil (100 cs) as a vitreous substitute compared to higher viscosity silicone oil (5000 cs)

“…Physicochemical characteristics of this silicone are summarized in Table 2. Despite the fact that this type of very low viscosity silicone is prone to earlier emulsification than higher viscosity silicone oil [21][22][23], no toxic effects on the retina were demonstrated in }he rabbit up to 5 months. Actually we did not observe emulsification of this sil- icone oil in these eyes followed for up to 5 months, when cataract developed.…”

The Use of Continuous Silicone Oil Infusion as a Peroperative Tool to Facilitate Break Localisation, Vitreous Base Dissection and Drainage of Subretinal Fluid

“…Such a low-molecular-weight component could promote emulsification [7]. It was necessary in all instances to go through an air/silicone infusion exchange to make sure that the very last droplet of oil was removed.…”