Glaucoma tube implant surgery involves inserting a device into the eye which lowers the eye pressure by draining fluid out.
There are a few types of Glaucoma tube implants, all of which have a small tube as well as a larger plate attached. The two main types of tubes used worldwide are the Ahmed and Baerveldt tubes. Studies have shown that the Baerveldt tube is more effective in lowering the eye pressure compared with the Ahmed tube, likely because it has a larger plate than the Ahmed. However, there are more complications associated with the Baerveldt tube, including a higher risk of low eye pressure which can result in vision loss.
In recent years, we have a new tube called the Paul Glaucoma Implant, or PGI for short. It has a smaller inner tube size of 0.1mm compared with 0.3mm for the Ahmed and Baerveldt tubes. The plate size of the PGI is larger than the Ahmed and more similar to the Baerveldt tube. Hence, early studies suggest that the efficacy of the PGI may be similar to the Baerveldt and better than the Ahmed, with a low rate of complications including low eye pressure.
Your eye surgeon makes an incision in the conjunctiva, the outermost layer covering the white part of the eye. This allows the tube implant to be inserted underneath the conjunctiva. The plate is stitched to the sclera, the white outer wall of the eye. The tube is then inserted into the eye, stitched to the sclera and covered with a patch as well as with conjunctiva. After tube implant surgery, fluid flows out of the eye through the tube and spreads over the plate.
Tube implant surgery is an effective glaucoma surgery for lowering the eye pressure, but as with any procedure, there are potential complications. It is important to discuss these with your eye surgeon in detail.