Nuclear magnetic resonance analysis of emulsified silicone oil RMN-3 (Oxane HD).

BACKGROUND: Oxane HD is a mixture of 5700 cs silicone oil and RMN-3 (a partly fluorinated olefin), which has a specific gravity greater than water, thereby enabling endotamponade of inferior retinal breaks. Droplets of emulsified oil were found in the anterior chamber of two patients with complex retinal detachments who had been treated with Oxane HD. Samples removed from these two eyes were analysed in order to investigate the nature of the emulsified substance. METHODS: Samples were dissolved in CDCl3 and, if necessary, dried using magnesium sulphate. Nuclear magnetic resonance (NMR) was used to compare these samples with the unused commercial product. RESULTS: NMR analysis of the samples removed from the anterior segment of both eyes were mainly silicone oil with only trace amounts of RMN-3. Samples taken from different areas of an unused syringe of Oxane HD demonstrated varying concentrations of the RMN-3 compound within the silicone oil. CONCLUSION: First, the mixture of RMN-3 and silicone oil is not homogenous either in vitro or in vivo. Second, emulsified oil found in the anterior chamber is composed almost entirely of silicone oil, containing only trace amounts of RMN-3.

Mass and shape as factors in intraocular foreign body injuries.

OBJECTIVES: To relate the nature, mass, and shape of intraocular foreign bodies (IOFBs) in a consecutive series of 69 patients to the mechanism, location, and visual outcome of the injuries and to compare these outcomes with data collected in our department over the last 70 years. DESIGN: Interventional case series of consecutive patients with IOFBs. PARTICIPANTS: Sixty-nine patients with unilateral IOFBs. INTERVENTION: All patients underwent surgical removal of the IOFB. MAIN OUTCOME MEASURES: Patient data included best-corrected visual acuity (BCVA), imaging and complication rates. For the IOFBs, material, mass, shape, and entry site were determined. RESULTS: The IOFB was metallic in 91% of cases. All but 2 patients were male (mean age, 37). Increasing IOFB mass was associated with posterior segment injury, retinal impact, presenting and final BCVAs< or =20/200, the need for a primary globe repair before secondary IOFB removal, increasing complications, and the development of retinal detachment. Blade-shaped IOFBs penetrated to the posterior segment (97%) more frequently (P<0.05) than disc (74%), cylinder (7.5%), or sphere (7.5%) shapes despite having the second lowest mass. Two patients were shown to have a second previously unrecognized IOFB on computed tomography (CT). Overall, 49% of patients experienced some sort of complication as a result of their injury. The development of endophthalmitis was associated with the failure to use prophylactic systemic antibiotics. There was no association between increased time to IOFB removal and the development of endophthalmitis. The frequency of posterior vitreous detachment was not increased in eyes with more severe injury or those in which surgery was deferred. Final BCVA> or =20/40 was achieved in 56% of the patients. CONCLUSIONS: Intraocular foreign bodies of greater mass were associated with worse outcomes. We have observed an 82% reduction in number of IOFB injuries presenting over the last 70 years and outcomes have improved with advances in surgical technique. We advise that all patients with a visible or suspected IOFB be investigated with x-ray or CT and that they should all receive systemic antibiotics. We detected no advantage or disadvantage in delaying surgery until optimal surgical expertise and/or environment is available.