Intraocular sustained drug delivery using implantable polymeric devices

Vitreoretinal diseases involving age-related macular degeneration (AMD) are refractory to most topical or systemic drugs. The retina and the vitreous cavity have a unique position regarding pharmacokinetics in that the inner and outer blood retinal barriers separate the retina and vitreous from the systemic circulation. Eye drops achieve minimal therapeutic concentrations in the vitreoretinal tissue. Drug delivery systems are a strategy to address this. Intraocular sustained drug release using implantable devices has been investigated to treat vitreoretinal diseases. Possible targeted diseases include those in which repeated intraocular injections are effective (cytomegalovirus retinitis, uveitis), diseases requiring surgery (proliferative vitreoretinopathy), and chronic diseases (AMD, macular edema, retinitis pigmentosa). Hydrophobic or hydrophilic polymers shaped into a sheet, disc, rod, plug, or a larger device can be implanted into the subretinal space, intrascleral space, vitreous space, peribulbar space, or at the pars plana. Many researchers suggest the feasibility of these implants to treat AMD.