An injection device for injecting a material into tissue may include a sheath having a distal end. The injection device may also include an injector having an outlet tube. The outlet tube may be received in the sheath, and may include a distal portion with a penetrating tip for penetrating the tissue. The sheath and the outlet tube may be slidable relative to each other, to extend a length of the distal portion from the distal end. The injection device may also include an adjuster operatively coupled to at least one of the sheath and the outlet tube. The adjuster may be configured to control relative movement between the sheath and the outlet tube for selectively adjusting the extended length.