Filtering Surgery – Trabeculectomy and Tube Implant Surgery – These types of surgery are performed to allow fluid to drain from the eye into a pocket on the outside of the eyeball, yet not into the tear film. The “pocket” drains into the blood vessels and lymphatics around the eye, not into the tear film. These surgeries are the most powerful of the surgeries for glaucoma. There are risks to the surgery, so this surgery is reserved for patients with progressive disease, or very high pressure. SEE LECTURE #4. A variation or trabeculectomy uses a metal shunt in the opening usually made as a simple hole in standard trabeculectomy. This is the X-press shunt. Results similar to trabeculectomy are usually achieved. These types of surgery are performed in the operating room.
Tube Implant surgery – This is a variation of the filtering surgery above. A tube is inserted into the front chamber of the eye. The other end is attached to a “plate” where the fluid exiting through the tube ends. It forces the bleb to be as large as the size of the plate. The plate is sewn onto the eyeball on the back half of the eyeball, between the muscles that move the eye. A patch graft is usually sewn over the tube near the front of the eye to protect it from coming through the conjunctiva which covers the white of the eye, the plate and the tube so it is not felt by the patient. This device (also called a Seton device) is usually performed if a trabeculectomy cannot be perfomed or fails. Some surgeons prefer the tube implant to trabeculectomy.
Bleb Needling – This surgery is performed in the office in most cases. It can be used to revive or enhance a previous trabeculectomy bleb. ie it can only be performed in the presence of a previous filtering bleb after trabeculectomy.
Non- penetrating surgery ie Deep Sclerectomy, Canaloplasty, attempts to bypass the drainage obstruction in the fine meshwork of the angle of the eye and the collector channels. The hope is that the pressure can be lowered without a bleb. Popular in Europe, deep sclerectomy is often performed instead of trabeculectomy with good results rivaling trabeculectomy, but these results have not been seen in the US, and these surgeries are not often performed except by some surgeons who feel their results are excellent. The problem is that an incision similar to trabeculectomy may preclude a later attempt to perform trabeculectomy.
Minimally invasive glaucoma surgery (MIGS) is a class of surgeries only recently developed. Much attention is being placed on this new type of surgery involving the use of new devices to lower the pressure by bypassing the resistance to outflow from the eye. A large amount of investment capital and marketing to physicians is underway in developing them. The potential advantage would be that that the eye would not be scarred from these surgeries allowing standard trabeculectomy to later be performed. One device so far has been approved by the FDA, but its use is restricted to only at the same time cataract surgery is performed. SEE OUR BLOG ON THIS SUBJECT