Academic literature on the topic 'Buttonhole technique'

Most glaucoma specialists advocate the use of 5-fluorouracil (5-FU) and mitomycin-C (MMC) in various concentrations during the intraoperative and postoperative periods to help inhibit postoperative scarring, the primary cause of filtration surgery failure. Although the increased use of antifibrotic agents as adjunctive therapy to guarded filtration surgery has improved the likelihood of operative success, there are many additional complications associated with this class of medications. It is the nature of filtration surgery as it is performed today that successful drainage of aqueous comes with a price. Any adjunct that improves the intraocular pressure (IOP)-lowering success of surgery must be assessed in light of this increased risk. A leaking bleb is one of the most common complications seen after trabeculectomy and may occur at any point postoperatively. This complication has been reported with an incidence ranging between 17% and 42% according to one review. More recent estimates have been somewhat lower, at between 8% and 14.6%. The longer the postoperative follow-up, the greater the cumulative likelihood of bleb leakage. It is imperative that the bleb be checked periodically for leaks, primarily through examination and standard Seidel testing. Use of antifibrotic therapy is associated with increased formation of thin-walled cystic blebs, which are more likely to result in both short-term and long-term complications. The timing of a bleb leak will dictate management. Many early postoperative bleb leaks resolve without intervention but can significantly decrease the likelihood of trabeculectomy success. Early postoperative bleb leaks are often attributed to surgical technique and can generally be avoided by use of appropriate blunt instruments and careful attention to surgical detail. The simple use of nontoothed forceps when handling the conjunctiva can prevent small buttonhole conjunctival tears, which often result in early postoperative bleb leaks. However, even with careful manipulation, friable conjunctival tissue can be prone to small tears. While some have advocated the use of light cautery, or even tissue adhesives to close bleb leaks, the use of such techniques has diminished in the antifibrotic era. Intraoperative suturing of buttonholes is definitive.

Successful tube shunt surgery requires adequate coverage of the implant with conjunctiva. When a patient’s conjunctiva is tight or scarred, preventing exposure of the large plate and tube becomes difficult. In these challenging cases, the glaucoma surgeon must modify the surgical approach and apply surgical techniques that may be more familiar to cornea and oculoplastic surgeons than glaucoma surgeons. Any patient who has undergone ocular surgery involving the conjunctiva (e.g., cataract extraction through a scleral tunnel, guarded filtration surgery, pars plana vitrectomy, penetrating keratoplasty, pterygium excision, strabismus surgery) is likely to have conjunctival scarring. Additionally, patients with a history of inflammation of the conjunctiva may have thin, friable tissue that is difficult to manipulate. Other conditions that may lead to inadequate conjunctiva for coverage are chronic conjunctivitis, chemical burns, ocular cicatricial pemphigoid, Stevens-Johnson syndrome, and rheumatoid arthritis. In cases with marginal conjunctiva, the required conjunctival incisions and dissection for implantation of the device are performed, followed by assessment of the amount and viability of tissue. Only when adequate tissue is found should the shunt be placed. If adequate tissue is not available, the procedure may be aborted for an alternate choice. When a careful slit-lamp exam reveals conjunctival scarring to be localized, one may choose, preoperatively, to insert the tube shunt in an unaffected quadrant. However, in some instances, this approach is not possible due to diffuse scarring. Previous glaucoma surgery or posterior segment surgery (e.g., pars plana vitrectomy with silicone oil) may necessitate placement of the implant in a specific quadrant. When scarring affects the limbus, it may be difficult to initiate dissection of a fornix-based conjunctival flap without creating conjunctival buttonholes. Alternatives include making a more posterior limbus-based conjunctival flap, creating a superficial partial-thickness scleral flap, or even removing the scarred conjunctiva/Tenon’s layers and covering the defect with a conjunctival advancement flap. If upon examination the conjunctiva at the limbus cannot be easily mobilized with a sponge or blunt forceps, a limbus-based flap may be fashioned by making the initial incision 4–8 mm posterior to the limbus.