Needling and Revision Complications

Needle revision refers to a surgical procedure in which a fine gauge needle or needle-knife is used to incise scar tissue in the vicinity of a filtration opening. Initially described for temporary relief of elevated intraocular pressure (IOP) in the case of encapsulated filtering blebs, needle revision has been used to establish flow in the setting of a nonexistent bleb, enhance aqueous flow when a bleb is present, and to alter tectonic features of a filtration bleb. Among the many advantages of needle revision are rapidity, low cost (especially when performed in the office), minimal preparation, and rapid recovery. Compared to full surgical revision, needle revision involves relatively little disruption of tissue, resulting in minimal inflammation. Needle revision can be used to rearrange bleb architecture to decrease bleb height, a bleb morphology that is associated with corneal dellen and dysesthesia (see Chapters 18 and 19). Flow can be redirected using needle revision to reduce flow through bleb leaks, which may result in closure and/or prevent reformation of “overhanging” blebs. Although incision of relatively thin scar tissue with a needle establishes fluid flow, scar reformation is likely to occur without some sort of inhibition of scar formation. The introduction of antifibrotics, such as 5-fluorouracil (5-FU) and mitomycin-C (MMC), and antiangiogenics, such as bevacizumab, have enhanced our ability to prevent reformation of scar tissue. Needle revision is a useful procedure that can revise bleb architecture and redirect fluid flow with little inflammation. Understanding complications associated with this procedure is important for an ultimately successful glaucoma procedure. Needle revision can be performed in a variety of settings: the operating room, complete with the operating microscope, full preparation, and draping; the office minor procedure room using the operating microscope; or even at the slit lamp in the examination lane. Procedure time, cost, and equipment preference and availability are among other factors that may influence the choice of venue. Anesthesia methods also vary. Topical anesthesia, subconjunctival block, and retrobulbar injection can all be used. Generally, topical anesthesia with viscous lidocaine is adequate in most patients.