The Glaucoma Drainage Devices: Types and Models
Glaucoma drainage devices are designed to divert aqueous humor from the anterior chamber to the subconjunctival space. In 1912 the first attempt was made by Zorab  with a silk thread for translimbal aqueous drainage, and subsequently attempts were made with gold , platinum , and tantalum , but the results were poor because of uncontrolled flow, hypotony, and foreign body inflammatory reaction. Molteno in 1969 introduced the concept of a device that consisted of a long acrylic tube attached to an acrylic plate sutured to the sclera adjacent to the limbus, but this had a high failure rate due to bleb perforation or end plate exposure . In 1973 Molteno introduced the concept of draining the aqueous away from the limbus , placing the end plate at the equatorial region, and all of the currently available glaucoma drainage devices are based on this concept.