EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
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20 EW NEWS & OPINION Pterygium continued from page 19 Figures 5 and 6. The graft is tucked into the subconjunctival space to provide its antifibrotic effects to Tenon's fascia, from which pterygium recurrence might arise Figures 10 and 11. Thrombin (black label vial) diluted with balanced salt solution is placed on the excision site, and fibrinogen (blue label vial) is placed on the stromal side of the autograft Fibrin adhesive preparation The surgical assistant and circulating nurse prepare the fibrin adhesive as follows. The (scrubbed, gloved) sur- gical assistant holds a sterile 1 cc syringe with an 18-gauge needle and draws up about 0.1 cc of fibrinogen solution in a sterile fashion from the fibrin sealant vial (blue label), which is held inverted by the (not scrubbed) circulating nurse. Note the outside of the vial is not sterile, but the top can be wiped with alcohol to facilitate a sterile transfer to the sur- gical field. The same is done with the thrombin sealant (black label vial) using a separate 1 cc syringe and separate 18-gauge needle. The surgical assistant should be careful to include as little air as possible in the fibrinogen syringe. Next, into the thrombin-filled syringe the assis- tant draws up an additional 0.9 cc of balanced salt solution and inverts the syringe several times to mix the two. The adhesive components are now ready for use. Figure 7. Amniotic membrane (red) does not cover the bare sclera defect Figure 8. From the superior limbus, the conjunctival autograft is cut free from the superior limbus Figures 12 and 13. The conjunctival autograft is inverted, mixing the adhesive components, and smoothed to approximate the edges of conjunctiva Source (all): John A. Hovanesian, M.D. Amniotic membrane application The bare sclera is now wetted with a few drops of balanced salt solution to allow the graft to hydrate and slide during the next steps. A small droplet of fibrinogen is placed on the surface of a Paton spatula. Using toothed forceps in one hand, the surgeon lifts the edge of conjunctiva to expose the potential space that was created around the bare sclera. This fibrinogen is then applied to the underside of the conjunctiva in the potential space (note no throm- bin is applied at this point). This fibrinogen will help retain the AMT graft in the next steps. Attention is directed back to Figure 9. The free conjunctival auto- graft is inverted on the cornea (note the yellow epithelial surface of graft shown against the corneal epithelium) and oriented limbus-to-limbus adjacent to the excision site the amniotic membrane graft, which is removed from its packag- ing and placed on the bare sclera. Using toothed forceps, the surgeon lifts the conjunctiva to expose the potential space beneath it. At the same time, non-toothed forceps are used to grasp the edge of AMT and slide it from the bare sclera into the subconjunctival potential space (Figures 5 and 6). Care is taken to distribute the AMT evenly in this space, but some folds and turned corners of AMT are unavoidable and do not lead to problems after surgery. The surgeon's goal is to create a "beltway" of AMT in the subconjunctival space around the excision site but not covering the bare sclera (Figure 7). Once the AMT is in place, the surgeon can lift and advance the edges of surrounding conjunctiva toward the limbus to cover any rem- nants of AMT that are exposed. The presence of the fibrinogen, mixed with small amounts of thrombin in the patient's own blood, will allow these edges to stay in place, covering all of the AMT. Application of conjunctival autograft The conjunctival autograft, which remains attached to the superior limbus, is now reflected onto the cornea (epithelium to epithelium) and cut free from the superior lim- bus with scissors (Figure 8). The surgeon slides this graft across the cornea, orienting its limbal side to the limbus where the pterygium was removed (Figure 9). A small droplet from the diluted thrombin syringe (black label) is applied to the bare sclera (Figure 10), and a small droplet from the fibrinogen (blue label) syringe is applied to the un- derside of the graft (Figure 11). The graft is then grasped with two McPherson forceps and flipped onto the bare sclera site. This will mix the two components of adhesive, so the surgeon has approximately 30 sec- onds to "squeegee" the graft with the non-toothed forceps to orient it properly and approximate its edges with the edges of the surrounding conjunctiva and limbus (Figures 12 and 13). Once this is done, the surgeon should avoid unnecessary touching of the graft or surrounding conjunctiva, as this will only weaken the bonds of the fibrin ad- hesive. A fourth-generation fluoro- quinolone is used q.i.d. for 1 week; prednisolone acetate 1% is used q.i.d. for 2 weeks and then tapered over 2 weeks; and bromfenac is used b.i.d. for 1 week. Post-op follow-up/drug regimen • Fluoroquinolone eyedrops (Zymar, Allergan, Irvine, Calif.) q.i.d. for 1 week. • Prednisolone acetate 1% drops (Pred Forte, Allergan) q.i.d. for 2 weeks, then tapering off over 2 more weeks. • Bromfenac (Xibrom, ISTA Pharmaceuticals, Irvine, Calif.) b.i.d. for 1 week. • Return visit at 1 week. Pearls • Conservative use of cautery avoids post-op pain and is generally suffi- cient, as fibrin adhesive provides additional hemostasis. • Dilution of one part thrombin with nine parts balanced salt solu- tion slows down the polymeriza- tion process with fibrin adhesive and allows more time for manipu- continued on page 23 May 2012