Baerveldt Plate Area Comparison (BPAC)

This research is being done to compare the safety and effectiveness of two sizes of the Baerveldt glaucoma implant. A Baerveldt glaucoma implant is one of the most common types of glaucoma operations performed. This procedure works by providing a route by which fluid can drain out of the eye to decrease the intraocular pressure. The Baerveldt implant does this by placing a tube into the eye which shunts aqueous fluid to a silicone plate which is attached to the sclera (white portion of the eye). It is this plate that comes in two different sizes (250 square millimeters and 350 square millimeters). Earlier studies have shown that larger plate sizes produce lower eye pressures but that they may also result in more complications. While both Baerveldt devices are currently in use and have been shown to be safe and effective, it is unclear if one is superior to the other. The purpose of this study is to see if one size of device works better with fewer complications.