A device for injecting a therapeutic agent into an ocular implant at least partially implanted in an eye including an injection lumen providing a pathway for injecting the therapeutic agent into the implant； an outlet lumen providing a pathway for pre-existing fluid in the ocular implant to exit the implant； and a collection chamber fluidly coupled to the outlet lumen that provides a first fluid outflow resistance and a second fluid outflow resistance. The first fluid outflow resistance is lower than a first resistance to outflow of the implant. The second fluid outflow resistance is greater than a force imparted onto the implant by intraocular pressure of the eye. Injection of therapeutic agent into the implant via the injection lumen causes the pre-existing fluid to exit the implant and enter the collection chamber via the outlet lumen and causes a second pre-existing fluid to displace from the collection chamber.用於注射治療試劑到至少一部分被植入眼睛內之眼部植體之裝置包含：提供用於注射治療試劑至植體之路徑之注射管腔；提供對於在眼部植體內的預先存在的流體來離開植體之路徑之出口管腔；以及流體地耦接至出口管腔且提供第一流體流出阻力及第二流體流出阻力之收集腔室。第一流體流出阻力低於植體的流出之第一阻力。第二流體流出阻力大於藉由眼睛的眼壓傳至植體的力量。經由注射管腔至植體之治療試劑的注射導致預先存在的流體離開植體並經由出口管腔進入收集腔室，並且導致第二預先存在的流體從收集腔室移位。
