Fig. 3. A. Appearance immediately after insertion of hydroxyapatite implant--vascularization has not yet occurred. B. The hydroxyapatite implant becomes vascularized by ingrowth of blood vessels through the posterior defect in the scleral covering and the scleral windows, where the muscles are attached. Once complete vascularization has occurred, a hole is drilled through the anterior portion of the implant and a peg that is coupled to the implant is inserted. The channel becomes epithelialized.