Pathophyiology of and prophylaxi againt late Ahmed Glaucoma Valve occluion

PURPOE: To undertand the pathophyiology of late Ahmed Glaucoma Valve failure and devie trategie to minimize thi problem. METHOD: One hundred ixty eye that had undergone Ahmed Glaucoma Valve implant by one urgeon were retropectively reviewed. ix eye with late (greater than 3 month) Ahmed Glaucoma Valve occluion requiring operative intervention were identified. Two of thee eye underwent initial ucceful trancameral drainage tube irrigation and four initially required Ahmed Glaucoma Valve exchange. Intraoperative image, potoperative hitologic analyi, and Ahmed Glaucoma Valve handling experiment were performed. REULT: Two eye with late occluion (33%; 1.25% of total implant) were initially uccefully treated with irrigation alone. A gap between the valve cover and valve body junction allowed fibrovacular ingrowth and produced valve failure ultimately in five of ix eye (83%; 3.1% of total implant). Thi gap could be produced by graping the device along the center line, indenting the valve cover, and damaging the platic rivet attaching the valve cover to the valve body. Handling the Ahmed Glaucoma Valve outide thi “no touch zone” eliminated thi problem. CONCLUION: Leaflet adheion ha a low incidence and may be treated by trancameral drainage tube irrigation. Late onet dital occluion i bet treated by Ahmed Glaucoma Valve exchange with repect for the “no touch zone.” Repecting the “no touch zone” over the valve mechanim hould avoid creation of gap between the valve cover and valve body junction, which allow econdary fibrovacular ingrowth.