title: Towards better characterization and quantification of emulsification of silicone oil in vitro.
abstract: OBJECTIVE
  Emulsification is related to complications arising from silicone oil (SO) tamponade. Currently, there is no widely accepted method for testing the propensity of SO to emulsify that are physiologically realistic and quantitative.
  
  
  METHODS
  We compared different ways of inducing emulsification namely vortex mixing, sonication and homogenization. Silicone oil (SO) emulsification was quantitatively assessed using the Coulter counter and laser light scattering. The in vitro results are compared with the droplet size distribution profile of vitreous clinical washout. Conventional SO was compared with two novel SO blends with high-molecular-weight (HMW) additives (SOHMW2000and SOHMW5000).
  
  
  RESULTS
  Of the three methods for inducing emulsification, homogenization generated the most consistent emulsion samples with the smallest variance. The results from the Coulter counter measurement correlated strongly with the laser light scattering measurement within the range of 1 to 30 µm. The droplet size distribution profiles from human eyes were similar to that of emulsions generated in vitro by homogenization. The human size distribution profile was within the range of values obtained by the in vitro experiment. Compared to the conventional SO, the emulsion droplet counts for the new SO blends were significantly lower (SOHMW2000and SOHMW5000were 79% (±17%) and 49% (±18%) of the SO2000and SO5000, respectively; p = 0.03 and p = 0.002).
  
  
  CONCLUSIONS
  Emulsion generated in vitro by homogenization has similar droplet size profile as human eyes filled with SO. Using this method to induce emulsion, SO blends with HMW additives demonstrated less propensity to emulsification with lower droplet counts compared to conventional SO with similar shear viscosity.
authors: Department of Mechanical Engineering, Faculty of Engineering, University of Hong Kong, Hong Kong, Pokfulam, Hong Kong.|Department of Ophthalmology, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong, Pokfulam, Hong Kong.
authors: Yau Kei
authors: YK
authors: Chan
authors: Department of Eye and Vision Science, University of Liverpool, Liverpool, UK.|Department of Biotatistics, University of Liverpool, Liverpool, UK.
authors: Gabriela
authors: G
authors: Czanner
authors: Department of Mechanical Engineering, Faculty of Engineering, University of Hong Kong, Hong Kong, Pokfulam, Hong Kong.
authors: Ho Cheung
authors: HC
authors: Shum
authors: Department of Eye and Vision Science, University of Liverpool, Liverpool, UK.
authors: Rachel L
authors: RL
authors: Williams
authors: Singapore Eye Research Institute, National University of Singapore, Singapore, Singapore.|Centre for Eye Research Australia, University of Melbourne, Melbourne, Vic., Australia.
authors: Ning
authors: N
authors: Cheung
authors: Department of Ophthalmology, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong, Pokfulam, Hong Kong.|St Paul's Eye Unit, Royal Liverpool University Hospital, Liverpool, UK.
authors: David
authors: D
authors: Wong
mesh_terms: D004655:Emulsions / Q000737:chemistry*; D058450:Endotamponade; D006801:Humans; D012827:Silicone Oils / Q000737:chemistry*; D014783:Viscosity; D057586:Vitreoretinal Surgery
chemical_list: D004655:Emulsions; D012827:Silicone Oils
keywords: Coulter counter; emulsification; laser light scattering; silicone oil