2020–2021 BCSC Basic and Clinical Science Course™
10 Glaucoma
Chapter 13: Surgical Therapy for Glaucoma
Plate-Based Tube Shunt Surgery
Mechanism of Action
Plate-based tube implants are designed to shunt aqueous from the anterior chamber to a space-maintaining plate in the equatorial subconjunctival space. Broadly speaking, plate-based tube implants can be divided into valved and nonvalved types. The Ahmed Glaucoma Valve (New World Medical; Video 13-8) has 2 leaflets in the plate that are designed to separate when the IOP is above a certain level (approximately 8–12 mm Hg). When the pressure is lower, the leaflets come together, preventing flow through the tube. The nonvalved Baerveldt (Johnson & Johnson Vision Care, Inc.; Video 13-9) and Molteno (Molteno Ophthalmic Limited) implants have no restriction to flow from the tube to the plate.
VIDEO 13-8 Ahmed valve implantation.
Courtesy of Simon K. Law, MD, PharmD.
VIDEO 13-9 Baerveldt tube shunt implantation.
Courtesy of JoAnn A. Giaconi, MD.
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.