Which Silicone Oil Should we Use? New Evidence to Shed Light on our Choices

David Wong

Meeting:  2015 RANZCO


Date:      -

Session Title: Keynote Plenary

Session Time:      -

In the past, the choices were simple. Use oil or not, if so 1000 or 5000 cs. In the last few years, the choices have greatly increased._ Putting aside heavy silicone oil, there are new oils with high molecular weight PDMS components that claimed to be easier to inject and remove yet more resistant to silicone oil._ In this talk, I will present the evidence behind the new oils.

Method: The laboratory tests include quantification of emulsification resistant by Coulter Counter and Laser scatter methods._ The characteristics (size and number) profile of emulsification from patients and from in vitro experiments are presented._ A randomised controlled trial was carried out to compare the readiness of Siluron 2000 (1000 cs silicone oil with 5% of 423 kD oils) versus conventional 5000 cs in patients treated with vitrectomy for macular hole surgery. Lastly, the new technology platform “eye-on-a-chip” enabled oils to be tested using simulated human saccades in chambers lined with retinal ganglion cells. _

Results: Coulter Counter showed that virtually human emulsification from different patients have characteristic profiles._ Combined with Laser scattered methods, for the first time, complete characterisation of emulsification was possible._ Surprisingly, the majority of droplets are “invisible” being smaller than can be resolved by slit-lamp biomicroscopy or even under high magnification in the laboratory._ In vitro experiment confirms that the new oils are viscoelastics and are more resistant to emulsification. Taken together with the results of the randomised clinical trial, the evidence challenges some of our strongest convictions: that 5000 is more resistant to emulsification than 1000 cs silicone oil in patients.

Conclusion: It is hoped that presentation will influence our choice of tamponades and change our clinical practice.