The present invention provides devices, systems, and methods for delivery of an active agent into the eye of a subject. In one aspect, for example, an ocular active agent delivery device (10) can include an active agent reservoir (14) disposed in an annular housing (12), the annular housing (12) being configured to fit inside of a lens capsule and at least partially encircling a line of sight of an intraocular lens within the lens capsule. The device (10) can further include a semipermeable membrane (16) operatively coupled to the active agent reservoir (14), where the semipermeable membrane (16) is configured to allow diffusion of an active agent from the active agent reservoir (14). Additionally, a valve (18) can be operatively coupled to the active agent reservoir (14), where the valve (18) is configured to allow filling of the active agent reservoir (14) with an active agent.