title: A low-molecular-weight oil cleaner for removal of leftover silicone oil intraocular tamponade.
abstract: OBJECTIVE
  Silicone oil (SO) has been used as a long-term intraocular tamponade in treating retinal diseases for more than half a decade. However, its propensity to form tiny SO droplets is associated with a number of complications. Currently there is no effective way to remove such droplets from the eye cavity. In this work, a novel cleaner was developed for effective removal of these droplets.
  
  
  METHODS
  The cleaner promotes the formation of an oil-in-water-in-oil (O/W/O) double-emulsion that consists of the unwanted droplets as the innermost oil phase. The cleaner's ability to encapsulate SO droplets was tested using both in vitro microdevices and ex vivo porcine eye models. The efficiency of the cleaner in removing the SO droplets was quantified using the three-dimensional (3D) printed eye model. Both the volatility and in vitro cytotoxicity of the cleaner were evaluated on three retinal cell lines.
  
  
  RESULTS
  Cleaner 1.0 is volatile and has an evaporation rate of 0.14 mL/h at room temperature. The formation of O/W/O double-emulsion indicates the encapsulation of SO droplets by the cleaner. In the 3D printed eye model, rinsing with cleaner 1.0 led to a significant reduction of leftover SO droplets compared with 1× phosphate-buffered saline (PBS; P < 0.05; n = 6). Cleaner 1.0 did not cause significant cell death (3%-6%) compared with balance salt solution (BSS; 1%-3%) in all three cell lines. The reduction in the cell viability due to cleaner 1.0, relative to that of BSS, was significant only in ARPE-19 cells (27%; P < 0.05) but not in the other two cell lines (8% and 17%, respectively; P > 0.05).
  
  
  CONCLUSIONS
  The double-emulsification approach was effective in removing remnant droplets from the eye cavities, and the cleaner was compatible with common cell types encountered in human eyes. The mechanism of toxicity of the proposed cleaner is still unknown, therefore, further in vivo animal tests are needed for full evaluation of the physiological response before the proposed cleaner can be advanced to clinical trials for retinal surgeries.
authors.affiliation: Department of Mechanical Engineering, Faculty of Engineering, University of Hong Kong, Hong Kong Department of Ophthalmology, Li Ka Shing Faculty of Medicine, 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, Hong Kong.
authors.forename: David
authors.initials: D
authors.lastname: Wong
authors.affiliation: Department of Ophthalmology, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong.
authors.forename: Hiu Kwan
authors.initials: HK
authors.lastname: Yeung
authors.affiliation: Department of Mechanical Engineering, Faculty of Engineering, University of Hong Kong, Hong Kong.
authors.forename: Ping Kwan
authors.initials: PK
authors.lastname: Man
authors.affiliation: Department of Mechanical Engineering, Faculty of Engineering, University of Hong Kong, Hong Kong HKU-Shenzhen Institute of Research and Innovation (HKU-SIRI), Shenzhen, Guangdong, China.
authors.forename: Ho Cheung
authors.initials: HC
authors.lastname: Shum
mesh_terms: D000818:Animals; D004655:Emulsions / Q000008:administration & dosage; D058450:Endotamponade / Q000009:adverse effects*; D006801:Humans; D008970:Molecular Weight; D011183:Postoperative Complications / Q000628:therapy*; D012163:Retinal Detachment / Q000601:surgery*; D012827:Silicone Oils / Q000008:administration & dosage* / Q000737:chemistry; D013552:Swine; D014821:Vitrectomy / Q000009:adverse effects / Q000379:methods
chemical_list: D004655:Emulsions; D012827:Silicone Oils
keywords: double emulsion; emulsification; encapsulation; silicone oil; vitreoretinal surgery