title: Factors influencing the shear rate acting on silicone oil to cause silicone oil emulsification.
abstract: OBJECTIVE
  The shear force between silicone oil (SO) bubble and aqueous during eye movements may underlie the development of SO emulsification. This study examines factors that may affect such shear force induced by eye movements.
  
  
  METHODS
  A surface-modified model eye chamber was put under large-amplitude eye movements (amplitude 90°, angular velocity 360°/s, and a duration 300 ms). Agarose-made indentations were introduced to mimic the effect of encircling scleral buckle. Two SOs (1300 and 5000 centistokes [cSt]), three volumes (3, 4, and 5 mL), and two eye chambers (with and without indentation) were tested. Video recording was used to capture the movements of SO inside the model chamber under various conditions.
  
  
  RESULTS
  The presence of indentation within the eye chamber significantly reduced the velocity of SO movements relative to the eye chamber movements (P < 0.001). To a lesser extent, an increase in viscosity also had a significant effect in reducing the relative movements. No significant effect was observed for the extent of SO fill in the chamber.
  
  
  CONCLUSIONS
  Our experimental model suggests indentation within an eye, such as that created by scleral buckling, may have the greatest influence in reducing shear force induced by eye movements. Therefore, using an encircling scleral buckle may be similarly or more effective than using SO with higher viscosity in lowering the propensity to SO emulsification.
authors.affiliation: Department of Ophthalmology, Li Ka Shing Faculty of Medicine, University of Hong Kong, Pokfulam, Hong Kong Department of Mechanical Engineering, Faculty of Engineering, University of Hong Kong, Hong Kong.
authors.forename: Yau Kei
authors.initials: YK
authors.lastname: Chan
authors.affiliation: Department of Ophthalmology, Li Ka Shing Faculty of Medicine, University of Hong Kong, Pokfulam, Hong Kong Singapore Eye Research Institute, National University of Singapore, Singapore Centre for Eye Research Australia, University of Melbourne, Melbourne, Australia.
authors.forename: Ning
authors.initials: N
authors.lastname: Cheung
authors.affiliation: Department of Ophthalmology, Li Ka Shing Faculty of Medicine, University of Hong Kong, Pokfulam, Hong Kong.
authors.forename: David
authors.initials: D
authors.lastname: Wong
mesh_terms: D005133:Eye Movements / Q000187:drug effects*; D006801:Humans; D008954:Models, Biological; D012163:Retinal Detachment / Q000601:surgery*; D012591:Scleral Buckling / Q000379:methods*; D012827:Silicone Oils / Q000008:administration & dosage / Q000737:chemistry*; D014783:Viscosity
chemical_list: D012827:Silicone Oils
keywords: eye movements; retina; vitreoretinal surgery