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Jesse T McCann, Yale Fisher; Direct Visualization of Silicone Oil Removed From Vitrectomized Eyes with Transmission Electron Microscopy Reveals Microemulsions and Nanoemulsions. Invest. Ophthalmol. Vis. Sci. 2014;55(13):1933.
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Poly(dimethylsiloxane) polymers (commonly known as silicone oil) have been frequently used in retinal surgery as a tamponade. Emulsification of these oils has been a difficult and persistent problem. Persistence of the oil following vitrectomy with fluid exchange has been confirmed by contact B-scan ultrasonography. In addition, infiltration of the silicone oil into the retina and optic nerve has been demonstrated by SD-OCT and adaptive optics imaging. This study intends to directly visualize the emulsions formed by silicone oil used in retinal surgery by multimodal imaging.
Silicone oil that was removed from eyes by fluid exchange and vitrectomy having been used as a surgical tamponade was subjected to chemical and electron micrographic analysis. 0.1 mL of silicone oil was washed with 2 mL of sterile irrigating solution (BSS, Alcon, TX). The mixture was then vortexed for 60 s and allowed to sit at 25 °C for 24 hours. The supernatant was decanted and placed on carbon-coated copper grids for transmission electron microscopy (TEM) and cryo-TEM analysis.
BSS was sufficient to emulsify the removed silicone oil. Transmission electron microscopy revealed nano-size (<100 nm) and micron-sized (<1 µm) oil-in-water emulsions. These emulsions are several orders of magnitude smaller than previously reported. These droplet sizes are similar to the size of silicone oil droplets that have been found in the tissues of the retina and optic nerve using optical coherence tomography and adaptive optics imaging.
This demonstrates that silicone-soluble components of the eye partition into the silicone oil after its instillation as a surgical tamponade. These silicone-soluble components are alone sufficient to cause emulsification. The equilibration of the silicone oil with lipid-soluble components in the eye is consistent with phase-equilibrium behavior. Further analysis of the silicone oil to determine the identity of the emulsifying agents is ongoing.
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