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Emulsification of silicone oil and eye movements

Chan, Yau Kei; Ng, Chiu On; Knox, Paul C.; Garvey, Michael J.; Williams, Rachel L. and Wong, David (2011) Emulsification of silicone oil and eye movements. Investigative Ophthalmology and Vision Science, 52 (13). pp. 9721-9727. ISSN 1552-5783 (Online); 0146-0404 (Print)

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Abstract

Purpose: Emulsification is an inherent problem of silicone oil used in vitreoretinal surgery. It has been shown that silicone oil can be made more resistant to emulsification and easier to inject by adding high molecular weight components (5 or 10% 423kD polydimethylsiloxane) to normal 1,000mPa.s silicone oil. We hypothesize that this might also reduce the movement of oil within an eye. Methods: A model eye chamber made of surface-modified polymethymethacrylate was driven by a computer and a stepper motor to mimic saccadic eye movement. Seven silicone oils with different shear and extensional viscosities were tested. Two sets of eye movements were used: (amplitude 9o, angular velocity 390o/s, duration 50ms and amplitude 90o, angular velocity 360o/s, duration 300ms). The movements were captured and analysed by video recording. Results: The angular velocity of an oil bubble relative to the eye chamber appears to form an exponential relationship with its shear viscosity. Depending on the thickness of the film of aqueous between the eye wall and the oil bubble, the shear rate was estimated to be between 6 and 14 x 104s-1. The addition of 10% of 423kD polydimethylsiloxane to 1,000mPa.s silicone oil significantly reduced the peak relative velocity compared with the base oil of 1,000mPa.s but not 5,000mPa.s. Conclusion: The addition of high molecular components to a base oil increases its extensional and shear viscosity. Whilst the extensional viscosity affected the ease with which the oil could be injected, our results showed that it was the shear viscosity that determined the relative velocity between the oil and the wall of the vitreous cavity, and thus the propensity to emulsify.

Item Type:Article
Additional Information:Issue date: 24 December, 2011. Available online: 22 November, 2011.
Uncontrolled Keywords:eye movement; tamponade agents
Subjects:R Medicine > RE Ophthalmology
Departments, Research Centres and Related Units:Academic Faculties, Institutes and Research Centres > Faculty of Medicine > School of Health Sciences
DOI:10.1167/iovs.11-8586
Related URLs:
Refereed:Yes
Status:Published
ID Code:4833
Deposited On:05 Jan 2012 09:34
Last Modified:01 Nov 2012 15:59

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