Heavy silicone oils show potential in management of inferior retinal detachments R et in a U pd at e

HEAVY silicone oils have shown promising results in the treatment of retinal detachments in the inferior quadrant in several studies. However, their use remains controversial, attendees at a symposium at the 7th EURETINA Congress heard. Proponents of silicone oil say that the specific gravity of these compounds makes them more efficient than conventional silicone oils in providing inferior tamponade in the vitrectomised eye, and that they are more effective in treating proliferative vitreoretinopathy (PVR).They also do not require patients to maintain a face-down position for long periods after surgery, said David Wong FRCS, Royal Liverpool University Hospital, Liverpool, UK, who chaired the session. “There are those who say that heavy silicone oil is absolutely wonderful. Retinal detachment, they say, is caused by PVR and PVR has a predilection for the inferior fundus.Therefore, if you have a heavy silicone oil it will tackle this inferior PVR problem and increase your chance of successful repair of the retinal detachment,” he explained. On the other hand, critics of heavy silicone oils maintain that they are too sticky, making them hard to remove.They also point out that they are more prone to emulsification than standard silicone oil, which in turn gives rise to inflammation, Dr Wong noted. “It is the dispersion of tamponade agent into droplets that is largely responsible for the inflammation, quite apart from the fact that individual agents might be a stimulant for inflammatory reaction.The rationale behind the newer heavy silicone oils is that if we mix semi-fluorinated alkanes or alkenes and highly viscous silicone oils we will end up with a solution that is less likely to emulsify and therefore would be less inflammatory,” Dr Wong said. Among the newer heavy silicone oils that are currently available are Oxane HD® (Bausch and Lomb) and Densiron 68® (Fluoron). Oxane is a mixture of 5700cs silicone oil and RMN-3 (a partially fluorinated olefin) with a specific gravity of 1.02 and a viscosity of 3300-3500. Densiron is a solution of perfluorohexyloctane (F6H8) and 5000 mPas silicone oil, with a specific gravity of 1.06 and a viscosity of 1387 mPas. Recently published success rates with the two oils have varied but they also have had different study designs and different inclusion criteria.The future of heavy silicone oil may depend on the results of the multicentred randomised controlled trial that is currently under way comparing heavy silicone oil with conventional silicone oil. More than 40 surgeons in 23 centres are participating in this trial, Dr Wong said. “Newer products that have theoretical advantages over the currently available HSO are already being studied.The use of heavy silicone oil is surely gaining momentum,” he added.