Distribution of Triamcinolone Acetonide after Intravitreal Injection into Silicone Oil-Filled Eye
There is increasing use of the vitreous cavity as a reservoir for drug delivery. We study the intraocular migration and distribution of triamcinolone acetonide (TA) after injection into silicone oil tamponade agent during and after vitrectomy surgeryex vivo(pig eye) andin vitro(glass bottle). Forex vivoassessment, intraocular migration of TA was imaged using real-time FLASH MRI scans and high-resolution T2W imaging and thein vitromodel was monitored continuously with a video camera. Results of theex vivoexperiment showed that the TA droplet sank to the interface of silicone oil and aqueous almost immediately after injection and remained inside the silicone oil bubble for as long as 16 minutes. Thein vitroresults showed that, after the shrinkage of the droplet, TA gradually precipitated leaving only a lump of whitish crystalline residue inside the droplet for about 100 minutes. TA then quickly broke the interface and dispersed into the underlying aqueous within 15 seconds, which may result in a momentary increase of local TA concentration in the aqueous portion and potentially toxic to the retina. Our study suggests that silicone oil may not be a good candidate as a drug reservoir for drugs like TA.