ABSTRACT
The AGV is composed of a silicone drainage tube and a polypropylene or silicone reservoir body that houses a silicone elastomer valve membrane. The S-2 model and Ahmed Flexible plate (Figure 4.1) have a single plate (13×16 mm) with a surface area of 184 mm2; the double plate version, the B-1, has a combined surface area of 364 mm2 (a 12.2× 14.8 mm non-valved plate and a 13×16 mm valved plate (Figure 4.2)). A pars plana adapter is also available (Figure 4.3). Drainage tubes for all the implants have a 0.64 mm external diameter with a 0.30 mm internal diameter. The valve-like mechanism is designed to open only if the intraocular pressure (IOP) exceeds 8 mmHg, and will, thus, prevent hypotony in the majority of cases.
