Refillable Devices for Therapy of Ophthalmic Diseases

As a subset of ophthalmic drug delivery systems, refillable approaches encompass a relatively new but growing field of study. This review will cover general design considerations in the development of refill devices for the eye. This will include acceptability of administration sites, body and injection port design, influences of vacuum and pressure, flushing and fluid replacement for active, passive and solid delivery devices, and potential for contamination. Historical influences leading to the current design concepts such as development of parenteral infusion pumps, glaucoma drainage devices, and pioneering ocular experiments will be discussed. Finally, specific studies and designs on refillable systems that have been proposed to deliver agents either to the vitreous through the pars plana, via trans-scleral delivery from episcleral implantation, to subretinal or suprachoroidal spaces from anterior location or to the anterior or posterior chambers from the lens capsule will be presented.