Various hypotheses have been proposed. Mechanical pressure from the silicone oil may result in ischemia, said Lihteh Wu, M,.D., at the American Society of Retinal Specialists.
For decades, slicone oil tamponade during the procedure to treat a detached retina, which if left untreated or treated unsuccessfully can lead to blindness. Silicone oil has several characteristics that make it an excellent substance for holding the retina in place and preventing damaging leaks of fluid, and it is left in the eye for some time while the retina heals. However, there is also a long-recognized risk of vision loss, albeit it small, associated with silicone of tamponade.
In a presentation at the American Society of Retina Specialists on Friday Lihteh Wu, M.D. , a U.S.-trained retinal specialist who lives and practices in Costa Rica, reviewed the research on silicone oil tamponade and discussed the rise and falls of various hypotheses about the reasons occurs. Tamponade is a medical term for closing or blocking a wound or body cavity by — or as if by— a tampon, which has come to mean an absorbent vaginal insert to prevent menstrual bleeding but can refer to anything that that closes a wound or blocks bleeding.
In a brief interview after his presentation, Wu said in most retinal specialists prefer to use gas in uncomplicated cases of retinal detachment. “The thing with gas is that gas disappears spontaneously. The oil stays here until you’re pretty much sure the retina heals in place,” he said.
Wu said one hypothesis that didn’t pan out was that silicone oil disrupted the ability of Müller cells to siphon off potassium ions into the vitreous so the ions accumulated in the subretinal space. Another resulted in the creation of charged potassium ions that damage the eye. Another theory that fell by the wayside is that the silicone oil resulted in transmission of high-energy blue light, particularly in aphakic eyes.
Although it is not a completely settled issue, Wu said the explanation for vision loss from silicone oil tamponade that currently seems most plausible is the oil causes some pressure that results in ischemia. Retinal specialists don’t need to stop using silicone oil tamponade but should be careful about leaving the oil in the eye too long.
“Whenever you feel that the oil has accomplish what it needs to, just take it out. Don't leave it longer than you need to,” Wu said.