Glaucoma drainage devices: a review of the past, present, and future.

Glaucoma drainage devices are more frequently being used for glaucoma filtering surgeries, even those at low risk for failure with trabeculectomy. There are 4 major devices available: the Molteno, Baerveldt, Krupin, and Ahmed. The Molteno and Baerveldt are non-valved implants, while the Krupin and Ahmed are valved. The success rates of the different valves are about equal at approximately 70% with a mean intraocular pressure (IOP) lowering of at least 50% from the pre-operative IOP. Unfortunately, the failure rate is about 10% per year, leading to only 50% functional drainage devices at 5 years. Therefore, research on the biomaterials, shape, and technique of drainage implant surgery is being done in hopes of increasing long term success rates.