Glaucoma is an eye condition that damages the optic nerve, which is responsible for sending visual information from your eye to your brain. This damage is often related to high pressure inside the eye, known as intraocular pressure (IOP). The eye constantly produces a clear fluid called aqueous humor, and if this fluid does not drain properly, pressure can build. While eye drops are a common treatment to lower IOP, for some, more advanced surgical interventions are necessary to manage the pressure and prevent further damage to the optic nerve.
What is a Baerveldt Glaucoma Implant
A Baerveldt Glaucoma Implant, or BGI, is a type of medical device known as a glaucoma drainage device. Its primary purpose is to lower intraocular pressure by creating a new pathway for the aqueous humor to drain from the eye. The device itself consists of two main parts: a very small, soft silicone tube and a larger, thin silicone plate. This design distinguishes it from other implants, some of which incorporate a valve mechanism to regulate fluid flow.
The BGI is considered a non-valved implant, meaning it does not have a built-in mechanism to prevent fluid from draining too quickly. The silicone tube is inserted into the front part of the eye, while the plate is positioned on the surface of the eye, underneath the eyelid. This plate functions as a reservoir, creating a space for the aqueous humor to collect before it is absorbed by the body’s tissues. The large surface area of the Baerveldt plate is a feature designed to facilitate a controlled, long-term reduction in eye pressure.
Candidate Selection for BGI Surgery
The decision to proceed with a Baerveldt Glaucoma Implant is not made for every person with glaucoma; it is typically reserved for more complex cases where other treatments have not been successful. BGI surgery is often considered for individuals with secondary glaucomas, which are types of glaucoma caused by other medical conditions or previous eye surgeries. This includes conditions like neovascular glaucoma, which can be a complication of diabetes, and uveitic glaucoma, which is associated with chronic eye inflammation.
Another significant group of candidates are those for whom a previous glaucoma surgery, such as a trabeculectomy, has failed. A trabeculectomy creates a new drainage channel for eye fluid, but it can sometimes fail due to the body’s natural healing process causing scar tissue to close the channel. Patients who have a tendency to form significant scar tissue may be better suited for a BGI. The implant is designed to be more resistant to closure by scarring, offering a more durable solution for long-term pressure control in these challenging situations.
The Surgical Implantation Process
The surgical implantation of a Baerveldt Glaucoma Implant is a detailed procedure performed in an operating room, often under local or general anesthesia. The surgeon begins by creating a small pocket under the conjunctiva, the clear tissue covering the white of the eye. This pocket is where the implant’s plate will be placed. The plate is then carefully sutured to the sclera, the white part of the eye, to hold it securely in place, typically about 8-10 mm back from the edge of the cornea.
A very small incision is made to allow the thin silicone tube to be inserted into the anterior chamber of the eye, the fluid-filled space at the front of the eye. A step in this surgery is the temporary closure of the tube. The surgeon will often use a dissolvable suture to tie off the tube, or place a stent inside it, to prevent the eye pressure from dropping too low immediately after the operation, a condition known as hypotony. This temporary blockage allows a fibrous capsule to form around the plate, which helps regulate fluid drainage once the suture dissolves weeks later.
Post-Operative Care and Long-Term Management
Following BGI surgery, patients enter a period of careful monitoring and recovery. This involves a strict regimen of eye drops, including steroids to control inflammation and antibiotics to prevent infection. Multiple follow-up visits are scheduled to monitor eye pressure and the healing process. Patients are advised to avoid strenuous activities, bending, and heavy lifting for several weeks to allow the eye to heal properly.
While BGI surgery is effective, it is not without potential complications. These can include hypotony, a spike in eye pressure, infection, or double vision (diplopia). In some cases, the tube can move too close to the cornea, potentially damaging the corneal endothelial cells over time.