Comparison of the Outcome of Silicone Ahmed Glaucoma Valve Implantation with a Surface Area between 96 and 184 mm2in Adult Eyes

Glaucoma is a leading cause of irreversible blindness worldwide [1]. For the surgical treatment of glaucoma, filtering surgery, such as trabeculectomy, is performed as a standard procedure. However, in cases of intractable glaucoma, including neovascular glaucoma, uveitic glaucoma, aphakic or intraocular lens glaucoma, and glaucoma after penetrating keratoplasty, it has been reported that the success rate of trabeculectomy is low [2-6]. An aqueous outflow device was first used to treat intractable glaucoma by Zorab in 1912 [7]. Since then, various aqueous outflow devices have been developed for intraocular pressure (IOP) reduction in glaucoma refractory to glaucoma filtering surgeries [8]. The Ahmed glaucoma valve (AGV; New World Medical Inc., Rancho Cucamonga, CA, USA) was introduced in 1993 as the first aqueous shunting device that has a unidirectional valve mechanism designed to prevent postoperative hypotony [9]. Currently, there are 2 types of AGVs that differ in their surface areas: 96 mm2 (FP8), which is generally used in children and 184 mm2 (FP7), which is generally used in adults. In the clinical setting, implantation of the FP7 AGV is challenging in adult eyes with conjunctival scarring or limited subconjunctival space owing to previous ocular surgeries, inflammatory ocular disorders, or small eyes. In these cases, the FP8 AGV is used instead of the FP7 AGV in adult eyes with glaucoma. Although silicone AGV is widely used, little is known about the differences in the efficacy and safety between the 2 models. If the FP7 and FP8 AGVs are similar in terms of efficacy and safety for treatment of adult glaucoma, using the FP8 AGV in adult eyes with insufficient conjunctival or subconjunctival condition could be a useful surgical option for IOP control. This study was performed to compare the postoperative outcomes between FP7 and FP8 AGV implants in adult eyes with glaucoma.