Surgical Treatment for Tube Erosion after Ahmed Valve Implantation

Abstract

Purpose: To report serial cases of patients who received surgical treatment for tube erosion after Ahmed valve implantation. Methods: In this retrospective and longitudinal study, surgical outcomes of reconstruction for tube erosion after Ahmed valve implantation were evaluated. Tube erosion occurred in 7 of 125 eyes (121 patients) at 60.5 ± 67.5 months (2 to 196 months). To prevent recurrence of tube erosion, the tube was repositioned backward in 4 eyes. Scleral allograft was used in all cases. Partial thickness scleral flap, collagen matrix implant, or bovine pericardium was used to cover the exposed tube in selected cases. In eyes with large conjunctival defects or severe adhesions between surrounding conjunctiva and episclera, rotational conjunctival flap, conjunctival autograft, or amniotic membrane graft was used to reconstruct the ocular surface. Results: Three of 7 eyes (42.9%) with tube erosion were successfully repaired by the first surgical treatment. No recurrence of tube erosion was found after the second and the fourth surgical procedure in 3 and 1 eyes, respectively. There was no case of explantation of the Ahmed valve in our series. Tube erosion recurred in 1 of the 4 eyes in which tube-repositioning was required and in 3 of the 5 eyes in which a partial thickness scleral flap was made to cover a tube. One eye experienced recurrent tube erosion in a relatively short-term interval and was repaired successfully using both collagen matrix implantation and amniotic membrane transplantation. Conclusions: Tube erosion after Ahmed valve implantation was successfully treated by various methods including tube repositioning, partial thickness scleral flap combined with scleral allograft, biodegradable collagen implant, pericardial graft, and/or amniotic membrane transplantation.