C Yoo, et al. PERICARDIUM PLUG IN CORNEOSCLERAL FISTULA REPAIR (Cosopt® and Alphagan-P®) were added postoperatively. During the postoperative 26 months, the anterior segment remained stable with IOP under control. D iscussio n Transconjunctival tube erosion is an infrequent but well-known complication of GDIs surgery. It is estimated that 2~7% of patients undergoing GDIs procedure develop melting of the overlying scleral or pericardial patch with erosion of the tube through the conjunctiva.8-13 Possible causes of conjunctival erosion include mechanical abrasion of the conjunctiva by the lid, excessive conjunctival tension over the tube, tube malposition, or lack of a smooth and tapered surface between the patch graft and the host along with poor ocular lubrication.10 Patch grafts like sclera, fascia lata, or dura mater may thin or disappear after implantation, secondary to ocular inflammation or a host-graft reaction.10 Pericardial patch grafts, which are supposed to be cell-free and without any antigenic stimuli, have also been reported to melt.4,10 Management of the exposed tube includes conjunctival autograft, scleral patch graft, amniotic membrane patch graft, and removal of the tube.3-6 If the tube exposure is accompanied by the infectious inflammatory signs which do not respond to antibiotics, the tube and the valve plate should be removed to help stop the propagation of the infectious process and prevent the subsequent development of endophthalmitis. Although the explantation of a GDIs is a simple procedure, it leaves an opening in the cornea and sclera that may not self-seal. If the GDIs has been implanted for a long period of time, it can be difficult to close the fistula which has been occupied by the tube.7 Mere direct sutures may close the defect. However, this would require a great amount of tissue tension and thus induce a significant amount of astigmatism which may be bothersome to an eye with good visual potential. Even if the fistula is sealed tight initially, there is still a chance that the fistula may recur later and lead to aqueous leakage if the suture is not strong enough to withstand the tissue tension. Therefore, tissue replacement may be an effective method to seal off the fistula, because it induces much less astigmatism postoperatively. Since the pericardium is highly biocompatible and provides an immediate and permanent seal, we used a pericardial plug to replace the corneoscleral fistula when explanting the AGV in all four of our cases. Since Sibayan et al.7 first description of this surgical technique, there has been no published report of utilization of this method and its postoperative results. In Sibayan et al. study, they presented only the postoperative fourth week outcome of a single case. Our present study demonstrates the postoperative results of four cases that were followed up for a longer period. No fistula-related complication such as wound inflammation, leakage, or pericardium melting has been noted in any of our cases till the latest postoperative follow-up ranging from 12 to 26 months. Although the number of cases in our study is fairly small and the follow-up period is still short to verify the efficacy and stability of the method, the preliminary data of our cases may give support to the use of pericardium plug in such aforementioned conditions. In conclusion, the pericardium plug seems to be an effective method in the repair of corneoscleral fistulas resulting from explantation of glaucoma valve implants. However, a prospective study of a larger number of cases with a long-term follow-up will be needed to ensure the stability of this method. References 1. Nguyen QH, Budenz DL, Parrish RK. Complications of Baerveldt glaucoma drainage implants. Arch Ophthalmol 1998;116:571-5. 2. Gedde SJ, Scott IU, Tabandeh H, et al. Late endophthalmitis associated with glaucoma drainage implants. Ophthalmology 2001;108:1323-27. 3. Tsai JC, Grajewski AL, Parrish RK. Surgical revision of glaucoma shunt implants. Ophthalmic Surg Lasers 1999;30:41-6. 4. Lama PJ, Fechtner RD. Tube erosion following insertion of a glaucoma drainage device with a pericardial patch graft. Arch Ophthalmol 1999;117:1243-4. 5. Ainsworth G, Rotchford A, Dua HS, King AJ. A novel use of amniotic membrane in the management of tube exposure following glaucoma tube shunt surgery. Br J Ophthalmol 2006;90:417-9. 6. Godfrey DG, Merritt JH, Fellman RL, Starita RJ. Interpolated conjunctival pedicle flaps for the treatment of exposed glaucoma drainage devices. Arch Ophthalmol 2003;121:1772-5. 7. Sibayan SA, Latina MA. The use of processed pericardium in the repair of corneo-scleral fistulas. Ophthalmic Surg Lasers 1997;28(4):334-5. 8. Ayyala RS, Zurakowski D, Smith JA, et al. A clinical study of the Ahmed glaucoma valve implant in advanced glaucoma. Ophthalmology 1998;105:1968-76. 9. Heuer DK, Lloyd MA, Abrams DA, et al. Which is better? One or two? A randomized clinical trial of single-plate versus double-plate Molteno implantation for glaucomas in aphakia and pseudophakia. Ophthalmology 1992;99:1512-9. 10. Heuer DK, Budenz D, Coleman A. Aqueous shunt tube erosion. J Glaucoma 2001;10:493-6. 11. Huang MC, Netland PA, Coleman AL, et al. Intermediate-term clinical experience with the Ahmed glaucoma valve implant. Am J Ophthalmol 1999;127:27-33. 12. Coleman AL, Mondino BJ, Wilson MR, Casey R. Clinical experience with the Ahmed glaucoma valve implant in eyes with prior or concurrent penetrating keratoplasties. Am J Ophthalmol 1997;123:54-61. 13. Siegner SW, Netland PA, Urban RC Jr, et al. Clinical experience with the Baerveldt glaucoma drainage implant. Ophthalmology 1995;102:1298-307. 271